QT - Unknown debugger type "No engine"

Recently I have re-installed QT (5.5.1 MSVC 2013, 32 bit, rev. b52c2f91f5) on my PC and installed the debugging tools of Microsoft.

QT (QT Creator) can auto-detect these just fine.

When trying to start the debugger with either the default shortcut F5 or clicking it manually, it throws an error that the debugger could not be run. (Compiling works fine, debugging not at all)

No debugger-engine of type "No engine" could be created.

(Running Windows 8.1 with VS2013/VS2015 installed - QT working with VS2013 32&64 bit).

On my work PC I did the same process a few weeks ago and had no problems at all.

What could cause this problem ? Yet I have only found questions with the same problem related to other compilers.