I recalled this morning having some trouble in the past, exactly what I don't recall. But, remembering it had something to do with Preferences, I found my bookmark to this article and followed the procedures here:

Resetting Finale's preferences (using a tool crashes Finale, etc.) – MakeMusic Help Center (zendesk.com)

I had to redo my Device setup under MIDI/Audio, of course, but now a score that wouldn't play last night is playing as expected.

Not sure whether there are other impacts that will become apparent only later, but will share them if so. Anyway, I wanted to share this in case others can benefit.

When anything happens "suddenly", there is normally a cause. With Win10, the cause is often the updaters that ran the night before corrupting paths. Resetting Preferences is often the cure but reinstalling Finale in the Default location is not unheard of.

With the Mac, it's usually something else running and a reboot often fixes the issue. In the rare cases it doesn't, a Safe Boot resets System Paths to default. If Finale consistently boots slowly after a Security Update (or the Mac in general), resetting the Launch Services should fix this. Besides resetting them for the whole machine, it resets them to default for each installed app. Besides individual apps suddenly becoming unresponsive, this fixes Macs that refuse to shut down without being forced (hold the power button) and those that take forever to boot (6 minutes boot time on my iMac Pro after the March 2020 Security update).

Reset Launch Services

1. Open Terminal and run these commands (Copy & Paste):
2. sudo /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -seed -lint -r -f -v -dump -domain local -domain system -domain user -domain network
3. (enter Admin password when prompted)
4. killall Dock
5. sudo mdutil -E /
6. Restart your Mac