I’m new to the pcp world and my first gun is a kral big max x in .25 I’ve only had it a month and shot it maybe 100 times now it is leaking air ( I’ve no idea where it’s leaking from and I’ve never taken a pcp apart )
PCPs come with a panoply of potential leaks -- at the pressure gauge, the cylinder cap, the bottle etc. Krals are well made guns but they sometimes incur valve leaks. I would suggest returning it if it still is under warranty.
If you shoot it down to below a certain LOW PRESSURE point it's likely to leak all the air out (which can be totally normal for any PCP) and likely be difficult to hand pump from ZERO pressure unless you cock it first or double load 2 pellets to block the transfer port to allow pumping from zero start pressure.
If you have zero air in the gun then I would try to screw the TWO bottles in tighter b4 refilling.