I am finding that of my many characters, all on the same account, that at least on occasion all do not see the same amount of cash. Of recent instance, one character summoned a banker and saw only twenty thousand when there should have been over one million. I have not done a lot of testing on this to find the "always" and "only" specifics.
I have mentioned shared bank plat having issues a few times in the past and have been ridiculed and told I was wrong etc. The worst cast scenario is when it disappears. The safest thing I found was simply not put any plat in shared bank. Parcel is safe or just give it to the other character.
never put anything in shared slots /PP included you are not prepared to lose.. it's been randomly buggy since forever. And yes, I say that, with full shared slots.. I know..but I never put PP there. PP always gets parcelled