I know it's miserable when you can't isolate the source of the problem. I was always reluctant to do a Factory Data Reset, but I became a believer following the update,on both of my devices
I was surprised to see how much less painless that operation is now, especially that it restored all of my home screen settings, widgets and app groups automatically. It's still a bit of work, but much improved, and it might help your problem.
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