I know this is much later than the original request, but thought I'd add this option for anyone new that might be searching.
- my RootsMagic worked fine
- I set up Microsoft Defender (security/antivirus in Windows 10)
- I turned on one extra thing that sounded good - "Controlled Folder Access" under Ransomeware
- tried RootsMagic again and it couldn't open the data - "unable to open database file (14)"
- tried changing "read only" properties, but didn't work
- went back into Defender and turned "Controlled Folder Access" back off
- RootsMagic came back to life
There may be other ways to get it to work with "Controlled Folder Access" still turned on, but this was enough for me.