I have an external disk which I use for data and a TimeMachine backup. For some reason the partition table appears to be broken and I may already have worsened the problem by trying to fix it with testdisk, where I went through EFI/GTP -> analyze -> quick search and tried to restore all partitions, which tells me the structure is bad, so I restored the first two. I'm not sure what EFI System is good for, if activated it is mounted, but that wasn't the case before the problems started.
The 4TB disk is split into two parts around 2TB each, both standard encrypted macOS partitions.
I already tried to follow HFS+ Partition of Mac OSX is not recognized in Windows 10 Bootcamp but when I try to add the second partition, it says
GPT partition #2 does not exist or is too big; skipping.
The same happened on another external disk. Both worked fine earlier today/a few days ago. The only change I see is that I used a different cable for one of the disks but not for the other.
So now that I have restarted my macbook, the second disk works again, whereas the first does not (presumably because I messed it up).
I would appreciate if someone can point me to a solution for this. Also I would be interested how this can happen at all.