Yeah and I believe this was fixed in v1.12 as you can see below. Best thing to do is put weak brigades or fort zones in forts that you don't want to have decay.
Appendix C - current max fort level and decay rules
● Max fort level:
○ 5.10 (3.10 in swamp) if fort above 4.10, or this hex contains a fort unit and port,
○ 4.10 (3.10 in swamp) if fort above 3.10, or this hex contains a fort unit,
○ 3.10 if fort above 2.10, or this hex is city, light urban, heavy urban, or adjacent hex contains a fort unit or enemy unit,
○ 2.10 if none of the conditions above are met.
○ Unless 4.10 or better is allowed, reduce max fort level to:
■ 2.10 if this hex is more than 25 hexes from supplied enemy combat units,
■ 1.10 if this hex is more than 50 hexes from supplied enemy combat units,
■ 0.00 if this hex is more than 75 hexes from supplied enemy combat units.
● Fort decay:
○ no decay if fort above 3.10,
○ no decay if not-depleted not-routed combat unit in hex,
○ up to 25% chance for no decay if fort above 2.10, otherwise:
■ base decay is 0.04,
■ x2 if there are no supplied enemy combat units within 25 hexes,
■ x4 if fort below 3.00 and weather is blizzard or mud,
■ x2 if fort below 3.00 and weather is snow,
■ x5 if fort below 1.00,
■ x3 if fort below 2.00.
< Message edited by redrum68 -- 10/28/2020 9:03:30 PM >