Can't tell you, the number of times I got a Zero "0" Grid (Patrol Area), in various mod set versions... instances, that come to mind are within LSH3 v15, notably... quite a few times, in fact.... NOT disparaging Urmels work by any means... just noting it did crop up in there
&... not sure but seem to recall it occurring in 1 of the other mod sets, but... which 1 exactly.. not sure, as it was.. many, many moons back, & just once... that I can recall of.
Main gist is... it can & does occur.
What I did, on them instances of it rearing its head, was... to simply shrug, shove off from whatever base I was at... head out to run a 'seek & destroy operation... making sure to sink as much as I could... before running out of ammo (see torps, deck gun) then... simply do an RTB... & move on.
M. M.