This is a problem with the Temp files. I have only seen it when Finale or its work files were stored on an external drive (including Dropbox, USB drive, thumb drive etc.). The Mac goes to sleep or otherwise loses the connection and cannot get it back. I am not certain that's the only cause.

If all of your work and the app is on your boot drive, then that can't be the issue. If, however, your work files are on externals, bring everything onboard and that should be the end of it. If not possible, do not let your Mac go to sleep—this fixes it for many. You can let the screen sleep without letting the Mac do the same. If your boot drive is an SSD, there's very little energy savings in letting your Mac sleep.

Here's a thread on another forum that addresses this.

https://www.finaleforum.com/viewtopic.php?f=5&t=15518