Workflow tasks not sending email & scheduler shows 'queued'

I’m trying to set up a workflow > send email so that when a new applicant (one of our new custom module, similar to ‘lead’) record is created, they get an email.
Currently nothing being sent and I’m not sure what the issue is.

Here’s what the workflow set up looks like:

When I checked scheduler, it shows that the ‘process workflow tasks’ job is queued:

Why is this queued, and how do I change this?

Thanks in advance!

Easiest way to get to work again is by making that job inactive and create a new one. That should allow the workflow to run as expected again. However you should be able to find the cause in your phplogs