Early in the first test, but it appears that my worker has "order" issues.
The "skip turn" icon indicator is permanently on. If I give the build road order, he will build the road, the go into automatic skip turn mode. Same with irrigate, as soon as the initial command order is completed, he goes into a stasis.
Also it appears, he is disabled from going into two tiles of terrain. At this point, I would have to assume it is relevant to smoke and heat (caused by nearby Earth Elementals). Other units can enter these tiles, but not my worker.
This "statis" effect occurs even during a step by step movement phase. If I command the worker to move one tile only (no movement penalty), it will not recognize it has a second movement point available, and go into statis.
Edit 1: Now this worker unit, can not enter a city to escape an attack by marauders. This is a different city then the area mentioned above, there are no elementals for that assumed effet.