Parallels 16.1.3 OpenGL object picking broken by OpenGL 3.0 upgrade

When I upgraded to Parallels 16, in a custom OpenGL application I use that uses mouse picking, the mouse picking stopped working. Setting video.gl3=0 made it work again. The mouse picking implementation is the usual method of rendering each object in a unique color.
The issue is that when an object (say a sphere) is rendered in a solid color with emissive material, the color read back using glReadPixels is no longer the same as what was written. I suspected Dithering was enabled, so disabled that, to no effect. Is there some other OpenGL option whose default has changed that might cause pixels to be modified without that being expected. Again, this used to work in Parallels 15 and also in 16 with the gl3=0 boot flag set.
Thanks in advance for any help.

 

Hello, could you reproduce the issue and collect the tech report right after that please?
Then please post the report's ID here.
Looking forward to your reply.