Tests are not getting distributed to agents in a location

Hello fellow WPTeers,

We have an internal instance running v17.12.0.402 on the WPT server and just upgraded our agents from v17.12.0.402 to v18.10.

We have 4 agents under a location called ‘us-west-prod’. They are all Windows 10 VMs hosted in AWS. Our WPT server is also hosted in AWS. Before upgrading the agents to 18.10, when I sent 4 requests to ‘runTest.php’, I would see all 4 agents get “busy”. However, now when I send the same 4 requests to ‘runTest.php’, only 1 agent gets work and the other 3 remain idle. It seems that my tests are all getting queued on that ONE agent. I can see all agents up and available in ‘getTesters.php’ and I can see a successful 200 response code in the terminal for the agents requesting work from the WPT server.

Craziest part is, that if I go to the WPT homepage and I execute tests from there (rather than from my integration), I DO in fact see the tests get load-balanced in the location and I see all 4 agents get busy.

Any help or ideas would be appreciated.