Invisible Monsters in Yanxia

I've encountered at least two so far that I could test, possibly more that I'm just missing entirely.

There are certain monsters that I cannot see or interact with, so far only in Yanxia. The first and most notable is the Pescatarian needed in a level 64 quest. It spawns on the beach upon surveying a destination, then proceeds to attack both me and my chocobo. Players I've brought to help me can't see it either, although no one else on the internet seems to be encountering this issue. I can see its name grayed out on the threat list, but there's no way for me to target it. My chocobo does not defend either me or itself against this enemy.

The second I've encountered was an A rank mob in Yanxia, Angada I think? I assembled with 20 some other players, and everyone but me could see it. I was able to get credit by healing people, and again, the monster appeared grayed out on the threat list. I couldn't actually see it or hit it.

There's also a B rank hunt I was trying to help someone find, swiftblade, I found the other B rank hunt several times during my search (Diedar I think). But I'm willing to chalk that up to me just not finding the hunt. I don't really care about it.

Anyway, since I can't seem to find anyone else with these issues affecting them personally, I was wondering if there are any technical steps to take to check to see if it's a problem with my client, or what.

I'm also unable to load up the level 54(or maybe 56) SAM duty in Costa Del Sol. (It loads in excess of 20 minutes at a black screen). Using an Alienware R-13 laptop that's 2 years old, so I doubt it's a technical spec issue. These problems happen regardless of Dx9 or 11 settings.

A complete reinstall has fixed all 3 issues. It also looks like this was an issue with a particular monster model which may have been corrupted the first time I installed Stormblood. It would have been nice if it didn't require a 3 hour reinstall. But for now the problem is fixed.