So, after a lot of troublesome research I managed to pinpoint the problem and it seems to be tied to number formatting in system settings.
In IT gold amount as well as XP is formatted using commas in contrast to how it looks like in the base game. That's why it worked for me in the latter but not in the former.
For anyone with similar issue, change your regional formatting settings to US in your Control Panel.

It's the original disc version fully patched. I can't use the Anniversary Edition because of my old PC
I tried all tricks with compatibility options also.