I've been working on this problem for a while and decided to ask the experts for help.
After the creation of a billing document, the revenue value field (VV010, user-defined; status: active) does not get updated. I have assigned the SD condition type PR00 to this value field. The COGS and quantity value field, on the other hand, do get updated. I would appreciate any help in this regard. If you need more details, I'd be glad to provide it.