No issues with 9.0.20 at all today.
I installed the update early this morning and Cubase has been running continuously since while I (on/off) worked a project. I must have mixdowned this project 15 times to get it right (to my ears). Again no issues. I have to say that this project is near completion so I really was not messing too much with adding/changing VSTs. Lots of small tweaks and edits though and, like I said, quite a few mixdowns. During this day long session I did not notice anything that made me think that I should not have installed it.