I have said this quite a few times before but it doesn't hurt to repeat it.
OUR Reaper VST3 model is (according to Justin hisself!) exactly following the Steinberg spec for same. To the letter.
Not even Steinberg have been that punctilious with their own plugs, apparently!
Which means that when we find a "broken" VST3 it is probably down to faulty implementation by the plugin devs, whether they choose to acknowledge it or not.
Mind you, I suppose Justin COULD be wrong....