@Ben @Juraj
I've been investigating the issue thoroughly and it really seems to be caused by 3ds Max file backup. When I had it disabled, I didn't encounter any resets even when I flew my mouse all over the place selecting and deselecting objects, turning sub-windows on and off.
While 3ds Max file backup was turned on, I was able to reproduce the same thing in Bens video. The thing here is that it's not always backing up files. It backed up whenever I selected and deselected an object (nothing else done to it, just select and deselect). But if I just move around with my mouse and change window focus, IR runs uninterupted.
Another thing would be Camera settings, I used CoronaCam, PhysCam, Target Cam and Free Cam. All with default settings. If you had other setting on your cameras, would you mind telling me? Or even better, if you still encounter this issue with disabled file back up. Would you mind sharing the scene itself?
Thank you very much