I had tried replugging the network (and Dante card) while it was locked. Nothing helped. This was on 1.81 firmware. Since updating to 1.88 the issue has not come back.
I managed to get the surface into a similar “half” locked state by assigning a softkey to “Go” and pressing it quickly 15-20 times to trigger through some scenes (the recall filter was only updating DCA/Group/FX routing, fader level, and DCA name – so not a lot of params). This would cause a lock up that it would not recover from. After updating to 1.88 doing the same thing was fine.