Ok I deleted a reply earlier because I thought I was hearing things, but I'm redoing it now because I have a vid. 

My original follow up said:
This may or may not help, but before going to the expedition map yesterday, I had been in/near one of the marketing rooms. There's a layout board in it that the assistant sometimes uses and there's a subtle scratching sound when they use a pen. There's no reason for it to be this sound, but it does sound oddly like it if it was on a loop... 🤔

Now I have a video with the sound of the dude writing on the board, and it does sound similar to the map screen issue. It's faint, so turn the volume way up with headphones, but it's there. 

I'm probably wrong, but it's a theory lol.

Also, the scratching sound showed up on other maps too, not just the sea one. There one minute, gone the next. That level is haunted. Appropriately! 🤣