I upgraded my MacBook Pro and when I try to save it says "The document "File Name" could not be saved. The file does not exist. Pretty straightforward. This is a file I work with all the time.
@"Vincent Edward Clark" I'm sorry to hear that. Can you try to fix this by giving mimoLive access to your entire hard drive?
Go to System Preferences -> Security & Privacy -> "Privacy"-tab -> select Full Disk Access in the left hand list and add mimoLive to the list of apps. (This is only to see if access rights are an issue. We do not access any of the data mentioned in the description of that feature.)
Please let me know if that helps.
If this does not help, please zip the document and send it to firstname.lastname@example.org so we can examine the file.