Reflect X cause occasional freezes/lockups. Could it be CBT?

My computer freezes/locks up randomly, about once a month, at night. It happens at 2:30am when Reflect X is scheduled to do its backups. I just find it frozen, no video signal, I have to pull the power plug to reboot it. Though I'm not 100% sure, I suspect it is Reflect X, the time lines up with the scheduled backups. It's not easy to reproduce, it happens randomly about once a month or so. The backup goes to an extra internal SSD drive, it's not any USB weirdness. Otherwise the computer is stable, I ran OCCT stress tests on it for hours and it doesn't crash during normal use.

I turned off CBT for now, that seems to be a kernel driver, maybe it has some rare bug that triggers these crashes.

Where should I look at logs perhaps there are clues where the crashes happen, which driver?

You should open a ticket with the Macri Reflect team. After all, you get unlimitrd full support as part of your lease.

CBT doesn't do those things...

What are those things?

Open Macrium Reflect and look at the log files. They'll show you what happens when your backups run. For any that have an error, you can look at Event Viewer to see what happened. Then, if you still have questions click on "Help". It will open links to both the Macrium Reflect manual and to the forums there.