Omnichannel routing for L1 and L2

I have approximately 200 categories of tickets (there are conditions on conditions on conditions in my form!) which can then be assigned to approximately 65 groups. Each group is made up of between 1-15 agents. We want to use round robin and are only taking in emails, no other channels.

All inbound emails will initially go to Level 1, so I've got a basic rule to route all new tickets to L1. Since these tickets then get assigned to a member of the L1 group, they move to open and are assigned to an agent (hence moving out of any queues). Once the L1 agent codes the ticket, it should then go through the omnichannel routing so it's routed to the relevant queue, and then assigned to an available agent in that queue (obviously the agents are assigned to a group which correlates to the queue).

Since the ticket needs to be unassigned to move from an L1 agent back into the queues, I've created a basic trigger to unassign the ticket. I've added a tag to my trigger to ensure it's being activated (as per image 1), but it's not unassigning (as per image 2). Is there a setting I'm missing?

When all agents are offline, I can make as many changes to the ticket as I wish, and it'll continually move the relevant queue (image 3).

Any help is greatly appreciated as I've been working with support for several days without a resolution!