256 colour support is broken on putty-0.59 (works on 0.58). I reported it upstream and a fix was applied today, simple typo. I will attach the patch Reproducible: Always
Created attachment 113778 [details, diff] Fix 256 colour support
Created attachment 113781 [details] Update ebuild to apply the patch
Fixed on 0.60, i suppose?
Try w/ 0.60 and reopen if needed.