I would suspect that a coup made by Vokic and Lorkovic would have been attempted, but IOTL it became unsuccessful.
Vokic-Lorkovic Coup
However, for this to even succeed, you would need the Allies to launch their invasion of the Balkans, which would mean a landing in Greece and Albania, as Churchill would have wanted.
The reason why I intentionally excluded Macedonia in this scenario is mostly because I'm not sure where they would fit in with this alternate post-war scenario. Would they stay with Bulgaria, even though the Bulgarians are on the losing side, or would they rejoin this new Yugoslav state that only consist of Serbia and Montenegro? Yes, given the large Partisan presence in Bosnia, I would suspect that their status would also be hazy as well.