BootCamp problem

What year is your Mac? Did you use Boot Camp Assistant to partition the drive? It should be a GUID Partition Map, not an MBR (Master Boot Record).

In macOS, can you post the output of the below command?

diskutil list

Odd. Your disk does seem to be partitioned with a GUID map. Can you try again, removing any partition BCA made (with Boot Camp Assistant, not Disk Utility), then re-partitioning?

Ah, OK. I would go ahead and remove the Windows partition and try again (but please, back up first!).

If it persists, I would recommend a full wipe and restore from your Time Machine backup-

Use Disk Utility to erase an Intel-based Mac - Apple Support

Restore your Mac from a backup - Apple Support

I see. Did you just reinstall macOS or did you erase the Mac too?

If you erased the Mac and the problem persists, you might want to seek service with one of the options below.

• Call Apple at 1-800-MY-APPLE or Apple Support at 1-800-APLCARE
• Chat using the Messages app on your iPhone or Mac. Make sure to use Safari to open the link.
• Contact - Official Apple Support
• Find Locations - Apple

It's OK! What do you see when opening Boot Camp Assistant? Does it ask you to partition the disk (seen below)....

...or does it ask you to restore partitions, as seen in the below screenshot?