2019 bug report and warning:

I was using the beta and cataloged my 2018 folder.  When the full release arrived, I used the plugin to migrate the enitre lightroom folder.  I then had both the Main folder AND the 2018 folder - which was a subfolder of Main in my cataloged folder, with the 2018 showing as fully cataloged (blue circle) and the main as not.  Quit and restarted, then thought I would trash my 2018 catalog.  It has thrown up a modal dialog box 'Removing Cataloged Folder' for several hours now, and although the app is not frozen (no red in force quit dialog), neither is it responsive.  The modal dialog is repositional, but otherwise non responsive.  It's single 'Cancel' button is greyed out, while activity Monito shows On1Photo Raw 2019 at 350% CPU, another app ON1Sandbox at 27%. Going to force quit and try again...