When you click F to garrison into a building, object’s hitbox can still “block” the building even though you can’t interact with those objects. For example, if you’ve set up an Outpost next to a woodline, if a tree, even a leafless one is standing infront of the Outpost, it’s massive hitbox will prevent your villagers from being able to F->Garrison into it.
Here is an example.
Suggestion: Villagers can’t interact with anything else when you press F. So make it so, that you can only target over garrisonable buildings when you’ve clicked F to garrison. Basically, make it ignore the hitbox of say, trees and other objects.
Why is this important? If one wishes to seek shelter for your villagers, there should never be a circumstance where things like this could happen. I’ve had this issue for a while and only now figured out why it was happening.