Not sure if you want this reported, and I'm not sure what happened, but I've got 4 spitters stuck in my base. They seem to be walking against the direction of the belts, what would explain them being stuck. But they also turn around, and should be able to move/ get moved automaticly.
Win 10 x64, zip version.
PS: I'm in no way trying to sabotage your goal of a stable 0.12, please don't be mad
It still works but i did notice increased number of belts destroyed. It is kinda annoying having to run all over defence system to fix that 1 belt all the time