Hi Roland,
Two major versions of the IDE are supported to be used side-by-side. Beta versions however are likely to have bugs or things that are work in progress, which can cause the problem you ran into it. It is for this reason we never recommend to install betas on your real/production environments. Please help us to open a support ticket so we can make sure the final release doesn't have this issue.
As far as skipping PB 2019 and going straight to PB 2021, I don't recommend you do this unless you want to use PowerServer. PowerServer is the only new feature of PB 2021 while PB 2019 R3 gets you long-term support. Per our product roadmap, PowerBuilder 2022 and its revisions are what will get significant new features for client/server projects.
Best regards,
Armeen
The problem with using 2019-R3 is that the installer screws up the earlier versions of 2019. We need to be able to support our customers using apps built with 2019 build 2170 while also working with a newer version of PB for future versions of our app.