[renowner]

Auto summon gives you the drain as a battle begins, as it summons before the round starts. But round 1 doesn't give you your fp regeneration or anything, so you pretty much start every battle with less than max FP. I assume this isn't intentional, but i'm not entirely certain.

[Neus]

Not sure if this qualifies as a bug exactly, since there are other effects that do activate at battle start this way. Things like Expert Aim, Always Wet, Shooting Stars, Fortune Vacuum, etc.