Newb question: Low resources in capitol

[Thrawn]

So, I'm playing in a PBEM, and we're around turn 25. The fortress in my capitol, for some reason, has way less resources than it used to. Only 85. I have all the provinces around it. Also, unrest is at 0 in all provinces.

Have I done something wrong to cause this resource deficiency? Are there stealthed enemy units that can sit in my capitol and drain my resources? I'm very confused, and it's REALLY killing my recruitment at a critical time.

Can anyone show a newb the light?