I have a project with both old Vision panels and new Perspective ones; if I open Vision first, all is good, but if I open Perspective first, attempting to open Vision will hang the designer.
Would it be possible to get a thread dump from your designer while it’s hung? You’ll need to install a JDK (any version should work, although some version of 11 would probably be best), then use some command line tool: https://blog.fastthread.io/2016/06/06/how-to-take-thread-dumps-7-options/
Okay, thanks for the report and the thread dumps - I’ve opened an internal ticket; we’ll have someone investigate.