PyCharm - All java imports are unresolved after upgrading to 2021.3 in Jython

Jython project using java libraries, including swing, and a linked java library.

All works fine in 2021.1

I've tried upgrading to 2021.2 and 2021.3 and I always get the same result.

All java imports get the dreaded wiggly red underline and reports 'Unresolved References'.

If I flip back to 2021.1, then all is fine.... I've tried this many times, I tinker with every setting I can find, but no joy?