I have not found this thread here so I thought I would share.
Valve has released an update about a few days ago. I know this is a late notice but I figured i post it now. Their latest update crashes any loading of maps that have ammopacks.
Now you can fix this by manually removing them using a notepad editor like notepad++. Here is an example of what I would find in a .vmf file.
You will need to remove all ammopacks. Medium, small, or large. just Ctrl + F “ammo” and remove each entity that comes up. You can then save it and load it in hammer. If ammo is a big issue at this moment for you just backup each ammo entity and add it again afterwords and use a different compiler.