After update to NC13 my app icons have all turned black!

Been running nicely on version 12.x for some while. I’d used the theming app to customise the colour scheme (we’re green, not blue). All good. The app icons were white against the green bar at the top of the page.

Today we updated to NC 13, and all is well apart from the fact that all our app icons are now black! It’s a minor point I know, but I can’t see any way to control this.

The docs appear to suggest that the icon colour is managed by a script based on other settings, although it’s not clear. Certainly it doesn’t seem to be controllable via CSS. I’d love to have my white icons black please. Any hints?

There is an issue with css/js caching, it might be worth trying if that fixes anything:

If that doesn’t fix it, can you temporarily disable your theme and check out the default one if it shows an error as well?