Deployment hangs for sample golang app

I’m unable to deploy the sample app from Run a Go App · Fly Docs

Running flyctl deploy basically just hangs forever. I’ve let it run for up to an hour with no luck. I tried re-running it with LOG_LEVEL=debug flyctl deploy and it looks like it’s just waiting on the remote builder:

DEBUG Sending remote builder heartbeat pulse to http://fdaa:1:26c0:a7b:c6ef:c26:dbed:2:8080/flyio/v1/extendDeadline...
DEBUG Remote builder heartbeat response: 202 Accepted
DEBUG Sending remote builder heartbeat pulse to http://fdaa:1:26c0:a7b:c6ef:c26:dbed:2:8080/flyio/v1/extendDeadline...
DEBUG Remote builder heartbeat response: 202 Accepted
DEBUG Sending remote builder heartbeat pulse to http://fdaa:1:26c0:a7b:c6ef:c26:dbed:2:8080/flyio/v1/extendDeadline...

Full output from the deploy command: flyctl deploy debugging · GitHub

(also, you can’t ctrl-c flyctl when it’s stuck in this state, you have to kill it with kill -9 which doesn’t seem great)

I’ve tried in both regions AMS and FRA, but it seems to be using the same remote builder each time.

Peeking at the monitoring stats for the remote builder in the web dashboard, it doesn’t seem like it’s overloaded. CPU usage and such seem low.

Any advice? Thanks in advance!