Vortex Crossfire 2 30mm

I have 2 vortex 1" scopes and 4 30mm scopes. 3 of the 4 30mm scopes keeping losing ability to hold zero. Anyone else having this problem?
I have not had that issue with my viper pst but I have to ask if it was on a springer?

The one side note I will leave, and not bashing per se. There will never be another vortex in my collection that is paid for, trade maybe. If asked I can elaborate a little but I'm not looking to put down the brand for tribal reasons.