I followed the tutorial on readthedocs and was able to get an experiment running on Heroku. I can access the ad for the experiment and run a debug session using the direct link to the Heroku app. When I use psiturk to create a HIT, it gets posted to the requester sandbox and it seems to be set up correctly. However, when I try to accept the hit as a sandbox Worker, the preview screen shows what seems to be a Heroku under construction page, with the text "There's nothing here, yet." and "Build Something Amazing". I can't figure out what's wrong; there doesn't seem to be anything in server.log, other than this message occasionally:
[2021-07-28 22:30:45 -0400]  [CRITICAL] WORKER TIMEOUT (pid:21040)
Any ideas for what I can try?