Deploy Artifact step just running endlessly

I've got a simple Deploy Artifact step for a deployment plan to the Testing stage, and it's just running endlessly with no output. I've tried a few times with the same results, then just this morning I set a timeout and retry limit, but it still looks the same. The promotion details seem to say that it is both "Awaiting Execution" and "in the process of being cancelled". I didn't set it to run in the future, and I didn't cancel it until it had been running for several hours without results.

Product: BuildMaster
Version: 4.2.8

Can you try running the BuildMaster service interactively to see if there are any more details written to the console?

I suspect if there's an issue here, it's related to 1 or more agents not being properly initialized.

Oddly, running the service in interactive mode seems to have solved the problem: the deployment is now complete. I didn't do anything but stop the service and start it interactively, and I didn't notice anything unusual in the output. It did look like it found the action and ran it, as far as I can tell, but didn't say what had been in the way.