All I can do is confirm this is the behavior I see on my machine. I tried removing the header information and re-adding it but nothing seems to make the Italic setting stick.
On a separate note, I’m curious why the European company got your code in pdf. The only reason I can think of that the line spacing/header info would make a hoot of difference would be if you’re trying to compare the old code with the new code side-by-side. Can’t you just take your copy (not pdf) of the old code and the current version and stick them in WinMerge and send them a diff file? You cold even make the diff file a pdf if that’s some sort of company requirement for sending them code. I hate to side track a topic, but I just had to ask.