[2022] Cannot access some (but unknown exactly how much) of DLC content G. Century - Example: Portuguese Navigators appear w/ incorrect benefit...

I'm not aware of any way that part of a DLC can be available but not other parts - it's all or nothing!

That said I'm not across the specific content you mention, as I've not played this game for several years. But we'd certainly know by now if this was a bug in Golden Century for instance.

Rio said: Running into some issues as Portugal, I checked out a couple of streamers and noted that as late as April and May of this year, people were talking about the flagship's Portuguese Navigator +100% range.

Cool, I say, that sounds like a good s'ploit-ish bandwagon to hop on... but... that option does not exist in my game for the portuguese flagship!

In my game, Portuguese Navigators get a 20% fleet attrition reduction (which either doesn't work or is so weak, it might as well not -indeed, sometimes it appears to work in reverse).

Could it be that depends on owning some other expansion you do not have? Or indeed vice versa?  

Can you try installing the game on any other machine you have access to, to see if it happens there too?