I assume that "150" is derived from Supply status x 5 ?
That is 'rule of thumb' as opposed to a precise value.
Also, the adjacent region controlled by GBR may be sending some supply [leaving it with 0]
From what you've posted, I still must say that the filter is a good indicator.
If after several turns, you see your supply status deteriorating, post a save with the several turns leading to that....
And please when posting saves: Send us the saved game with its current turn plus Backup1 Backup 2 etc as one zip:
[ATTACH]10164[/ATTACH]
If it's huge like this, send the files circled on the right, with \Backup1 etc. for as many turns as needed. If not sure, send the entire folder as circled on the left. Send email with these to
support@ageod.com