The Vantage point disappearing was addressed in 6.0.3.
I just tried putting a vantage point one map through Right Clicking > Set Info > Set Vantage Point.
I went to a different map and made a Vantage Point from Monitor > Set Info > Set Vantage Point
Restarted my machine and opened the maps in question and I was able to see the Vantage Point was still there.
Let me know if you see any issues with it on 6.0.3.