After Gallop/Star I got minus 560 prestige points applied, see picture.
I didn't do any action that costs prestige, so this bug is unrelated to any such action.
I'm not sure about the exact point in time when the negative points were applied.
Details in the chain of events that I'm sure of.
I finished Gallop/Star
Didn't do any moves, but quit instead
Restarted Unity of Command just like two minutes later
Then as I was to add specialist steps from force pool but could not, and started looking for clues to why not.
When viewing history, the history tells me I had +64 prestige points after doing the last move in Gallop/Star. And "-96" prestige points already before the first move in Orel/Briansk.
Actually: When I try to reload campaign at Orel/Briansk, the -560 points are removed. But when I then start Orel/Briansk again I start with "-96" prestige points, and when I look at the campaign map the -560 points have reappeared.
In the top picture you see I can't add a 120mm to the active unit. The force pools additions are supposed to be free, but I can't think of any other explanation than the negative prestige points. I then went back to the campaign map and took the bottom picture which has a line "Orel/Briansk -560". I'm not sure when that line appeared. I didn't notice that line before.
I continued playing, but the negative points spent stays put also after I conclude Orel/Briansk.
I'm using the Matrix version. I ran the updater after discovering this error to see if there was any new version, but the updater told me I already had the newest. Which is 1.02 according to the credits.