For reasons I won't explain, I have to change the word 'issues' to something different in our UI.
'Issues' corresponds to the number of map markers on a user's map.
Should 'issues' be changed to 'markers' or 'pins'? Is there a standard?
If these things are strongly correlated in users' minds to geographic locations, then I would certainly try to work "location" or "point" into the name. If these are reports of incidents or conditions, and only weakly correlated to geography, you might call them "issues", "reports", "incidents", etc. All the examples you gave seem to fall more into the latter category, but that's only a small sample set.
You don't have to use exactly the same terminology as Google Maps, etc., nor do you have to describe what this marker looks like ("pin") if that's just going to cloud the issue. If there is well-understood common nomenclature for something that everyone is using, and your thing is exactly the same sort of object with the same operations, then it would make sense to adopt the standard nomenclature. If there are some differences (even minor ones), it might be better to come up with your own name. This would avoid having people trying to apply what they learned elsewhere to your things, and having problems as a result.
You are probably asking this because your into implementing it as a developer. The API of the most used map, Google Maps, call these needles for "markers". I'd guess this is the most technically correct word to use.
Reference: Google Maps API Markers
However I guess your target audience isn't developers and in there daily life call the needles "Pins". And when they use it they "Drop a pin". To give you one example take a look at TripAdvisors' travel map and users quest to "Pin" locations where they've been.
Reference: TripAdvisor Travel Map pin location errors
If you know your target audience, you now know the correct word to use.
Given that users cannot place pins or markers themselves and you just want to give a different name for issues, I would go with place if there are only one and places if there are more than one. That way you don’t have to bother if it should be called a marker or pin, but abstracting the content to a more general word which represent what you really make visible – a place.
"Markers" is probably the best technical term.
"Pins" is probably the most common word in a non-technical, colloquial sense.
I tend to agree with @Benny in the sense that you should use what is most familiar to your users - however I don't think that that vast of a majority of users call it a "pin" as opposed to "marker".
But I'm just speculating, so go find out!
I think your solution should be to get a simple tally of what your users call them, and add "location" before the winner, ending up with either "Location Marker" or "Location Pin" which leaves little room to be misinterpreted.
What about calling them Points of interest? This is descriptive to your user, doesn't have a positive or negative connotation and is clear on what it means.
Using markers or pins is a good way to describe the icon, but what you want to describe is the actual location.
For this reason I would advise calling them:"points of interest", "locations" (as Andy Baughman suggests) or something descriptive of what the marker is showing.
Could you rename them to "locations" (or something similar), referring to the area that you are marking rather than the object that is doing the marking?
Markers used by Google and pins by Apple, where it really are a pins. So if you're writing about iOS and OSX, use pins, otherwise markers.