Hi tferratt,
What I reproduce here is much like yours, including:
1, 3 monitors
2, Revert to primary monitor after unlocking
3, Can not go to the 2-monitor topology until un-maxium and re-maxium
The only difference is that my display revert to the primary monitor after unlocking. No need to wait 10~20 seconds.
Hope the root cause is same to yours.