Agreed, could be the poppet face not sealing.
Also, sometimes when batteries get low, the solenoid can hang open venting air.
When I first bought my mini for what seemed like a steal, got it home, aired it up, and air vented/leaked out the barrel. It got fixed when I changed out the V2 poppet for a V3
Axe-Olive/Eigenbolt/CP Advantage/Eigenbarrel/7th Element OLED
Mini-Gloss Black/Eigenbolt/Violent Trigger
New England Lobsters