how can I prevent Cubase9.5 from changing Mono channels to Stereo

Hi everyone.
I have searched the forum and not found this specific question.
I apologize if it has been asked before.

When I open projects that were created in previous Cubase versions (8.5, 9.0), some of the mono tracks have become stereo tracks.
The mono inserts remain mono, which just create plain havoc with the stereo mix with left/right cancellations or interference/dropout.

I have not noticed exactly “when” this happens, but I think it occurs when I make a copy of the *.cpr file and then open it with 9.5.

I have read that there are issues with exporting a mono track to a stereo file because the mono track is routed to a stereo master group.
Could this explain why the actual mono channel itself because a stereo channel (containing a mono wave file)?

Is there any way to prevent this behavior?

Thank you everyone - changing the stereo tracks back to mono tracks (by creating new mono tracks for each and copying from the stereo to them) for large projects is tedious and time consuming and brings on “burnout” quickly!

I guess a follow on question is: Does Cubase want mono track audio to be on a stereo track?
Is that why the actual mono channel itself becomes a stereo channel containing a mono wave file?

Has anyone A/B’d whether a mono track with mono inserts sounds the same a if the mono wav file is on a stereo track with the same effects being used via the corresponding stereo plugin and settings?