Not sure if this happens all the time, but I saw an issue with False Life not providing the bonus HP after fast traveling. I was going back to the goblin courtyard after killing the bosses so I figured I'd prep for battle. My warlock cast False Life and then we used the portal into the goblin camp. When the battle started immediately, I noticed my character still had the icon for False Life but the secondary HP bar was missing and damage was hitting my regular HPs.
Can't speak for your situation, but I have not had that issue, at all, in playing a few Abjuration wizards who I typically always pre-buff with False Life coupled with Shield of Faith from [Great]Sword of Justice.
