I'm using Redhat Fedora 32 with Rosegarden 19.12 from the Fedora repo ( rosegarden4-19.12-1.fc32 ). The About dialog reports Version 19.12, Qt version 5.13.2. Everything seems to be working great with one exception: when I select File -> Manage Audio Files, Rosegarden segfaults. I'm unsure what other diagnostic information I can provide as it crashes immediately without offering any error message. I tried starting Rosegarden from the command line but no error message appeared there other than "Segmentation fault (core dumped)".
I can't reproduce this with 19.12 or the latest svn. Sounds like a distro issue.
I think the best thing to do would be to build Rosegarden yourself from the latest svn and see if that improves things. Not sure if you want to go that far, but if you do, the steps I use are here:
https://www.rosegardenmusic.com/wiki/dev:eclipse
It's Debian/Ubuntu oriented, so you might need to do things a little differently. We can help you through the process if you run into problems.
Haven't heard anything in a couple of months. Closing. Reopen if you'd like to continue working on this.