RAM filling up when in Multi User

If I’m using multi-user option in UE4. (2 machines connected and working on the same project)

The only app running is UE4 and it looks like when I persist and save the ram goes up but doesn’t drop back again. This keeps going until the ram is at 99% then after a few minutes UE crashes. Restart UE and all is fine until I start persisting/save again.

Is there some setting I need turned on?

As you can see in the attached video the RAM is being used up on a simple save action but not getting flushed once process is complete.