The Mautic jump condition is an amazing step in advanced customer journey campaigns, however there is a small bug which renders is useless (this was prevalent in versions up to 2.16.3 and I am not sure if it it is fixed in 3.x.
The Problem:
By adding a jump condition after a condition simply does not work. The jump is never triggered.
The Solution:
After a condition, add in an action step like “Update Tag” and changed the users tag to something and then add in the jump action.