Could be just a simple coincidence that is not releasing properly with the X50 version.
I had similar problem after 7 months of Leakshield, one day I just realised that my Leakshield is releasing the pressure very very slow, as you said, took like 2 min to do it.
To fix the problem I cleaned the membrane of the Leakshield with some alcohol, just use a piece of material and alcohol and easily clean the membrane, after that the Leakshield was working as new.