The Bug
This mod (Building Spawn Points) causes a bug with ground vehicles belonging to any building in the "Emergency Services" category in-game.

Important Points
-Fire stations are unable to keep track of there vehicles. #9152
-The Building Vehicle Monitor is also unable to see these vehicles. #9227
-The firetrucks themselves seem to have a home station, however. #9236 #9251
-Because the building does not keep track of how many trucks it has deployed, it can easily spawn more trucks than the building's intended maximum. #8677 #8717
-Disaster Response Units have the same issue with their road vehicles, but not with their helicopters, interestingly. #1584

Summary
When this mod is activated, fire stations lose the ability to keep track of what vehicles they have spawned, which also causes them to spawn more vehicles than intended.
The same issue also exists for disaster response units, however, it only affects the road vehicles, and not the helicopters.

How to Replicate: Fire
0. Have Natural Disasters DLC.
1. Have Building Spawn Points and (optional) Building Vehicle Monitor enabled.
2. Go into a pre-built city.
3. Find a relatively isolated district with at least 20-30 buildings.
4. Put a small fire station near it (such as the vanilla fire station) (so it has a low maximum number of trucks).
5. Disable any other nearby fire stations (so that the small fire station is closest to everything in the district).
6. Use the "Fire" tool in the natural disasters landscaping category to set several buildings on fire (you want to exceed the maximum number of trucks).
Now observe the first four points above.

How to Replicate: Disaster
0. See above #0.
1. See above #1.
2. See above #2.
3. Make sure there is only one enabled disaster response unit building.
4. Use the "Collapse" tool in the natural disasters landscaping category and collapse 20 or more buildings (that have road connections).
Now observe the last point above.

Notes
-This bug does not affect police stations, hospitals, pumping services, or anything else that I know of.
-It only occurs with Building Pawn Points active, and does not occur when it is not.
-Another confirmed report of this behavior can be found here.