Peter,
There are only very few VST3 plugins reported to have issues. Vast majority work fine. PGM will likely come up with a fix for those few that have issues. VST3 was long awaited. I am sure they want to get it right.

P.S. I don't have your particular strings, but I've tested Session Strings 2 with Kontakt 6.8, Kontakt 7 and Kontakt 8 in 2025 BIAB. They work as they should.