danoise, I already reported this many times now. A lot of bridged plugins do not work properly gui wise anymore in macos. Since 10.11 or so - so for a long time now. I really wonder why you never heard of this before? Didn't you read my bug reports?
FYI bitwig support says (also some 32 bit stuff not working anymore, but less than in Renoise), that the vst vendor has to fix their gui code for macos compatibility. Studio One in fact seems to blacklist some of those plugins now.
I am not sure if that is true. Most plugins work correctly in macos 10.9.
You can still use those plugins in non-gui mode.
So, if it is not fixable from Renoise side, is it possible to block the plugin gui opening with an additional entry/column in the plugin database? Since sometimes you still will open that gui, because you forgot that it does not work anymore. Then the gui process seems to hang, Renoise won't quit properly anymore.
Test system: macOS 10.13.4, HFS+. Firewire Audio, i7 4770, 8GB Ram, GTX1050 2GB, 48kHz