Based on my experience,
1. Not sure what's up with Hanna. That's a bit unusual, but her story recently got an overhaul, so that might be part of it.
2. You can only use the "talk" option once per character per in-game hour.
3. Some characters have their Kink Points and Love Points capped until you get to a certain point in their story.
4. The two most likely causes I can think of are a) you're trying to give out multiple gifts in the same in-game hour; or b) you're trying to give a gift to someone while they're at work.
So no, I don't believe most of that is due to a bug.