Derek

Assassin's Creed hasn't had a designated jump command since at least AC Origins. I can distinctly remember making Ezio jump by pressing X (Xbox), like 15 years ago, but the ability never really had any in game application.

I've only done one NPC mission, so I'm not sure if this applies, but for main story missions you have to scout the area you're searching in to reveal a marker on the map. Maybe it's the same for that particular side quest? Just spitballing, trying to help.

I also don't understand how you're getting stuck so much.