As the official update status thread doesn't reflect it yet: Traktor Pro 4.5.1 is available via Native Access. Fixes an issue and removes Windows 10 support.
Still no Phase HID support, still no OneLibrary, still no CDJ-3000X
But first signs of MX4:
But nothing happens, if I try to add the mapping. (EDIT: Just checked, was already there with 4.5.0 - just didn't saw that before.)