This happens with a camera memory for example, where photos are deleted and the name (such as P1010001.JPG) is re-used. The thumbnail image that Dolphin shows is from the earlier photo, although when the image is opened with Gwenview, it is the new image of the same name. Even if you F5 in Dolphin, it will not let go of the old thumbnail.
Portage 2.3.4 (python 3.4.6-final-0, default/linux/x86/13.0/desktop/plasma/systemd, gcc-5.4.0, glibc-2.24-r1, 4.7.4-gentoo-5 i686) ================================================================= System uname: Linux-4.7.4-gentoo-5-i686-Intel-R-_Core-TM-_i3-4010U_CPU_@_1.70GHz-with-gentoo-2.3 KiB Mem: 8203836 total, 4072424 free KiB Swap: 0 total, 0 free Timestamp of repository gentoo: Thu, 16 Mar 2017 22:15:01 +0000 sh bash 4.4_p12 ld GNU ld (Gentoo 2.27 p1.0) 2.27 app-shells/bash: 4.4_p12::gentoo dev-java/java-config: 2.2.0-r3::gentoo dev-lang/perl: 5.24.1-r1::gentoo dev-lang/python: 2.7.13::gentoo, 3.4.6::gentoo dev-util/cmake: 3.7.2::gentoo dev-util/pkgconfig: 0.29.1::gentoo sys-apps/baselayout: 2.3::gentoo sys-apps/openrc: 0.24.1::gentoo sys-apps/sandbox: 2.10-r4::gentoo sys-devel/autoconf: 2.13::gentoo, 2.69-r2::gentoo sys-devel/automake: 1.13.4-r1::gentoo, 1.15-r2::gentoo sys-devel/binutils: 2.27::gentoo sys-devel/gcc: 5.4.0-r3::gentoo sys-devel/gcc-config: 1.8-r1::gentoo sys-devel/libtool: 2.4.6-r3::gentoo sys-devel/make: 4.2.1::gentoo sys-kernel/linux-headers: 4.10::gentoo (virtual/os-headers) sys-libs/glibc: 2.24-r1::gentoo Repositories: gentoo location: /usr/portage sync-type: rsync sync-uri: rsync://rsync.gentoo.org/gentoo-portage priority: -1000 Installed sets: @base, @kde5-metal, @powerful, @scala, @wayland ACCEPT_KEYWORDS="x86 ~x86" ACCEPT_LICENSE="* -@EULA" CBUILD="i686-pc-linux-gnu" CFLAGS="-O2 -march=native -pipe -fomit-frame-pointer" CHOST="i686-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/share/config /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/php/apache2-php7.1/ext-active/ /etc/php/cgi-php7.1/ext-active/ /etc/php/cli-php7.1/ext-active/ /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-O2 -march=native -pipe -fomit-frame-pointer" DISTDIR="/usr/portage/distfiles" FCFLAGS="-O2 -march=i686 -pipe" FEATURES="assume-digests binpkg-logs config-protect-if-modified distlocks ebuild-locks fixlafiles merge-sync news parallel-fetch preserve-libs protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync" FFLAGS="-O2 -march=i686 -pipe" GENTOO_MIRRORS="http://ftp.swin.edu.au/gentoo http://mirror.pacific.net.au/linux/Gentoo ftp://ftp.swin.edu.au/gentoo ftp://mirror.pacific.net.au/linux/Gentoo " LANG="en_GB.utf8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j5 -s" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git" PORTAGE_TMPDIR="/tmp" USE="3dnow 3dnowext X a52 aac acl acpi ada aio alsa autoipd avahi berkdb branding bzip2 cairo cdda cdr cli colord cracklib crypt cups cxx dbus declarative disk-partition doc dri dts dv dvb dvd dvdr embedded emboss encode exif extras fam firefox flac fontconfig foomatic fortran freerdp gbm gd gdbm gif git glamor glibc-omitfp gnutls gpm gstreamer gtk gtk3 handbook iconv imap inotify iscsi java jpeg jpeg2k kde kipi kpathsea kwallet lame latex lcms ldap libnotify lzma lzo mad mercurial mmap mms mng modules mp3 mp4 mpeg msn musepack ncurses nfs nfsv41 nls nntp npp nptl odbc ogg openexr opengl openmp oscar oss pam pango pcre pdf phonon plasma png policykit postgres ppds pulseaudio qml qt5 quicktime rdesktop readline real rss sasl sdl sdl2 seccomp semantic-desktop session slang smime spam-report spamassassin spell sql ssh ssl startup-notification subversion svg systemd taglib tcpd theora threads tiff truetype udev udisks unicode upower usb v4l2 vaapi vcd vim-syntax vnc vorbis wavpack wayland webkit widgets win32codecs wmf wxwidgets x264 x86 xattr xcb xcomposite xface xine xinerama xml xmp xnest xpm xscreensaver xv xvid yahoo zlib" ABI_X86="32" ALSA_CARDS="atiixp" APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias" CALLIGRA_FEATURES="kexi words flow plan sheets stage tables krita karbon braindump author" COLLECTD_PLUGINS="df interface irq load memory rrdtool swap syslog" CPU_FLAGS_X86="aes avx fma3 mmx mmxext popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3" CURL_SSL="gnutls" ELIBC="glibc" GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt gpsclock isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="evdev" KERNEL="linux" L10N="en en-GB" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LINGUAS="en en_GB" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-6" PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_4" RUBY_TARGETS="ruby21" USERLAND="GNU" VIDEO_CARDS="intel i965" XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark dhcpmac delude chaos account" Unset: CC, CPPFLAGS, CTARGET, CXX, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
Please check in upstream at https://bugs.kde.org/show_bug.cgi?id=374829
Yes, probably related; for simplicity, let's close this as a duplicate.
Thanks for reporting. This is an upstream issue not downstream packaging related.
