I have tried using `genlop -c` on Linux, Mac OS X and Solaris. It will always report "no working merge found", regardless of what emerge says.
It's been like this for ages. :)
Can I see the FEATURES line from emerge --info from affected hosts?
Here is FEATURES from ~sparc64-solaris:
FEATURES="assume-digests binpkg-logs collision-protect config-protect-if-modified distlocks ebuild-locks fixlafiles force-prefix merge-sync news nodoc noinfo parallel-fetch parallel-install preserve-libs protect-owned sfperms strict test test-fail-continue unknown-features-warn unmerge-logs unmerge-orphans userfetch"