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?