This is not normal behavior. Sounds like it may be a hardware issue. I'd first back everything up, create a High Sierra USB boot disk and wipe and reinstall the

This is not normal behavior. Sounds like it may be a hardware issue. I'd first back everything up, create a High Sierra USB boot disk and wipe and reinstall the OS and apps. It's possible something went bad with the filesystem migration, and if that's the case, this should fix it. If not, then it's a hardware issue.