The spring loaded pin on the mini volt has a wider than normal flat head than most other spring pins, I notice I cannot use one of my 510 ego adapters on the mod due to that, it causes it to short on the thread portion. The mini volt only displays "check atomizer" , so it could be shorting out or as you put it "not making connection"
No, this would be to incompatible Pin height.
Regardless of center pin diameter, if the attaching device has a properly extended pin, proper contact will be made.
Looking at the Mini Volt and the Moonshot:
The problem appears to be the Moonshine having a Short 510 thread section and very thin 510 center pin.
The Tank and Mod Cannot make contact.
The use of a proper 510 extension would be required and the Tank will Not sit flush.