Same over here, and i think a lot of people are touched by it, i guess it's just a matter of time before people hit the bug since the patch was Yesterday.
I think the problem is from the editor, something in the update messed the AI grid in some ways. Since even a "clean" setup meet the same problem.
For now i think the best is to not generate the AI grid for those (like me) who intend to keep mapping even with this bug. This mean "no testing" but this is better than having your work bugged.
Let's report this to Larian asap.