I am not sure where this "Automatic Erase Disc" is. But if this is on the installer, I've never used it. I always used 'manual' or 'advanced' partitioning, sorry.
But, if it is what I think it does, this may have made your whole disk not 'pre-partitioned' as neither msdos partitioning and neither gpt partitioning. If that is the case, we will need to set the disk right first before we created any partiions in it. . And that may be the problem you are seeing. Your disk is not set right. And any subsequent OS install (as you point out) will also have the same problem.
But if you got it working, we are fine with it.
Oh, we appreciate your help in informing us how you fix the issue you're facing.
Cheers, take care, and welcome to Manjaro.
 - to set up disk partitioning, use gparted, at 'device tab' (at top of gui table), select 'msdos' or 'gpt' partitioning.
Note this will erase everything and partitions in disk. Then only create partitions in it.