Possible Script oversight? (Baktria tribute & negotiations)

As Baktria you are supposed to pay a yearly tribute (a very nice feature by the way!).
Unfortunately it seems as if that tribute isn't given after the first time anymore.
You click on "Accept" (as in "pay tribute) but the money isn't taken from your treasury.

Possibly related: when you demand payment (for example in exchange for a ceasefire), sometimes the other party agrees to pay, but the money never shows up in your treasury. Happened to me with Epeiros (Qart-Hadasht not paying), Baktria (Saka), Qart-Hadasht (Areuakoi after betraying me), so it seems not faction-related.

Hm.
For some odd reason I can't find the file where that repeated event script is located. Can anyone point me out to it?
I'd like to check the script to see if I can find a reason for the script firing just once instead of every four turns.

Without this money loss the campaign is a bit easy for Baktria (on H/M).