Unexpectedly signing out while using v14.1.18533

FYI: I am a private end-user. I say this because I do not want there to be any confusion as to my using TeamViewer for my own private use. I have been a TeamViewer since version 10.

I have just upgraded to v14.1.18533 and it seems to be working  fine with one glaring exception: of the 3 iMacs running this version (upgraded all at the same time), the most important one (ain't that always the hitch) seems to sign out by itself (when the iMac has been idle) after an unspecified amount of time passes. It's very annoying when attempting to access the iMac from my other location (using one of my 2 other iMacs running the same version and receiving this: "Computer Not running TeamViewer at this time" or something to that effect. I thought it was a power glitch until after returning to the location of the 'important' iMac only to find that it had indeed signed out by itself and all I needed to was to re-sign in. Note that the 'Stay Signed In" box is checked as is the 'Start TeamViewer with System' box. The confusing part of this is that the other 2 iMacs don't seem to have this problem. Is there a preference that I am missing? Suggestions, please?

Note: All of my iMacs were upgraded from v12.x.xxxxx.

One more thing: After upgrading to v14.1.18533 on my 'important' iMac, I remotely (while separately logged in to each one of the distant iMacs) upgraded them with no problems encounterd. I am truly at a loss and would appreciate some help.

Thanks,

alan