I came across a bug two days ago that I actually haven't seen since the game debuted. I was doing my typical "grab all the globes first" run on my way to the Lucky 38 (since Mr. House rarely survives long haha), and I noticed Hoover Dam never registered as a location. There was no XP given, no denotation on the map - it was if it didn't exist. I went about my travels but even returning later didn't fix it.

Is this a known issue, and is there a way to resolve it? It's not a huge deal to me as thus far it's the only spot that's done this, and I've never seen this happen prior.

Sometimes I had to walk a little down the dam for it to register

Well, I kinda panicked at first and did just that. Traditionally, it has registered for me as I walked down the road to the dam and always before the visitor's center. When it didn't, I walked past the event area and artillery area for quite a ways - I would dare say 100 yards or more. I never got the Undiscovered Location Marker on my way there either.

If I recall correctly there is some kind of bug that kinda erases the Dam map marker after a quest, I think it's after one of the NCR-mainquest-parts..