Some LH2 tanks loose fuel INSIDE the hangar fairing O_o

[allista]

Could it be that I should not put a self-propellant vessel with tanks and engines using hydrolox inside a hangar fairing?

The tanks got radiators, but something else was borked - the tanks only got 20% LH2 left as I deployed the vessel from the hangar fairing - about 10 minutes after launch. (The stages before didn't use LH2)

So I wonder if LH2 tanks are the culprit?

If only probes with RCS are allowed then the purpose of the hangar fairing is getting smaller for me.