I have a similar issue posted in the Android forum, perhaps it's relevant, perhaps not.
I always need to type in my MasterPassword, even though I've set it to not do so for 59 hours! It doesn't matter which AutoLock scenario I choose (either Enpass is idle, or System is idle).
As I mentioned in my other post, I am syncing with OwnCloud, as that seems to be the only thing that might be relevant to this issue.
Any ideas?
Thanks,
Craig.