Ok, i tried a developer snapshot(7.99.21) like always and i'm stuck because of a problem in sysinst. The NetBSD Bootloader can start Windows 10 without problems but during the installation i got the known problem "Old BPB too bug, use -f (may invalidate file system)". So I cannot start NetBSD but Windows 10 works.
There are some comments on the mailing lists for this problem:
here.