Any idea on missing preview in RW8.9.4

I migrated from an old MacPro (10.13.6) to a newer iMac (10.15.3). My RW8.9.4 app does not give previews of my projects. The older RW7 that also came with the migration assistent on the other hand gives the preview normal.
What to do? Complete reïnstall (via appCleaner) or erase some plists??

To much junk came with the migration tool. Started over this time a clean install and putting apps back by hand. Rapidweaver functions now normal. But i have to search on my carbon copy clone of my old ssd for all the pluginns and stacks. greetings dirk