(2012 VW GTI) Boost leak test not developing pressure

Hi all,

I have been trying to perform a boost leak test on my 2012 VW GTI. I have no reason to suspect there are any major leaks based on how the car drives, but I want to confirm that everything is working as intended. I'm using hardware from https://turboboostleaktesters.com/, coupled directly to the turbo inlet (not the air intake near the MAF). For air I'm using a portable battery-powered air compressor. Following instructions as I've seen them online, I've clamped the silicon hose from the tester kit directly onto the turbo's inlet, removed the oil cap, and started adding air. No matter what, the needle on my pressure gauge never gets close to lifting off zero (and I tested and confirmed the pressure gauge works). There are no hissing sounds of air leaking out anywhere, so clearly air is flowing out somewhere as fast as my compressor can pump it in. From my previous research I found that this can happen if the intake and exhaust valves are both open when you're pressurizing, so manually cranked the engine over, but no matter what position I would crank it to, I couldn't develop so much as 1 psi. Is there some other step that I'm missing? I feel like if this was just due to a giant leak somewhere I would notice something was off when driving, so I'm pretty confused as to where the air could be going.