Mercenary retraining

Hi all,

I've come across an oddity and was wondering whether its fixable through one of the files (doesn't seem to be the case via the descr_mercenaries but I might have missed it):

Mercenary crossbows and Frankish knights can only be retrained if their experience count is maximally 1 silver (exp4). Otherwise they will not even show up on the retraining screen of a region which has them available for hire as mercs.

Other mercenaries such as Alan Light Cav, Armenian Heavy Cav, Elephants and Turkopoles do not seem to have that issue at all.

In the descr mercenaries file, all of them are hired at exp0, so that shouldn't actually be the problem, should it? What is causing this discrepancy?