Leads stuck on Journey during a merge

Leads stuck on Journey during a merge

Hello, 

When my leads are going through a Journey, they get stuck on a merge for a very long time. I had a 1 hour delay for an email and it took an extra 30-45 minutes to move forwards after the merge.

One also got stuck for over 3 hours when there is no delay in place for the next step.

Is there anything I can do to move these along to the next step or do I have to just wait until they move along themselves.