This is a user-to-user forum, so we can only respond to what has been posted, here, which isn't a lot to go on, other than your LR Classic crashes after about a minute and you're on a Mac and have tried disabling the GPU. A couple more things to try would be: 1) Create a new, empty catalog and see if things are ok. 2) Pause Address Lookup, Face Detection and CC Sync, restart LR and see if things are stable for more than a minute. Then enable each of those settings one at a time, restarting in between, and wait for a minute or two and see if the crash is related to one of those things. I'm on a PC not a Mac so am not quite sure what all you can do on a Mac but if there is some way to find out what files the LR process is reading and writing to at the moment of the crash, perhaps it is related to a bad video or image file that LR is trying to examine as part of the background process of seeing if metadata has changed outside of LR.
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