Yep, it’s a real pity I didn’t upload a Saved Game when I had the chance. It happened with both Lean-to’s next to the Tower on the All for One map, so I thought it’s a general bug, easily reproducible. I tried a gain the map, but didn’t reoccur.
This is a good example maybe of why I created suggestion suggestion 45 in the Missing features thread. I think the resources for Lean-to might be generated at map start (?), and if that is the case, I could have used a save at game start (which would not get overwritten by End Turn saves later on).
That should be good enough for now. Until L13 formula was variating too much anyway, so I guess you just set hard values (?) and left the implementation of the formula for higher levels for later. Anyway, many thanks for all the fixes! 
