I've found a couple of apps in z18 where some text is black on a black background, here's an example from the 'Passwords and Keys' app:
Other areas of that app display just fine.
I also had a similar issue in Filezilla (apt version), where folders & files were black until they had focus at which point they would then show as white. However that issue seems to have resolved itself.
I did add this entry in .bashrc to modify 'other writeable' directory colours in bash/terminal to improve readability, but I don't think that should have affected other applications?
Not a major issue as it seems very localised and not sure if this is a bug or if it's something that can be user modified.
My initial hunch is that it might relate to apps that use an older/specific version of gtk.
Anyone have any thoughts on this?