Make OS X Partition active from Windows I have recently noticed, that I needed more space on my Bootcamp drive, so I unallocated 10 GiB in macOS using DiskPart. After that I rebooted into Windows and used "MiniTool Partition Wizard" to assign that space to the Windows partition.
It rebooted and expanded the partition as I expected, but afterwards I wasn't able to boot into my macOS again. It is cleary still there, but it seems, that I have to set a flag to make it bootable again.
Also booting into Recovery Mode doesn't work anymore - it's loading very, very slowly and gets stuck at 100% (I even left my notebook over night).

Does anyone know, how to set this flag using Windows?
I have fixed this issue myself, using a tool called gdisk. I converted the partition table back to GPT. The only problem now is, that i can see the recovery partition from the normal system and i can't really boot to it. No big deal for me, because I can use my mac normally again.