exercism submit doesn't update exercise

`exercism submit` reports a successful submission, but the exercise on the web isn't updated.

I've checked the URL from `Firefox` and `Chromium` and made sure to clear the cache in both browsers.

```
exercism submit src/beer_song.h src/beer_song.c

Your solution has been submitted successfully.
View it at:

https://exercism.io/my/solutions/4bef136f08184be7946ecbbcf0af40f1
```

Output of `exercism troubleshoot`:
```
exercism troubleshoot 222102

Troubleshooting Information
===========================

Version
----------------
Current: 3.0.11
Latest: 3.0.11

Operating System
----------------
OS: linux
Architecture: amd64

Configuration
----------------
Home: /home/dwrz
Workspace: /home/dwrz/path/to/exercism/workspace
Config: /home/dwrz/.config/exercism
API key: ************************************

API Reachability
----------------

GitHub:
* https://api.github.com
* [connected]
* 26.870463ms

Exercism:
* https://api.exercism.io/v1/ping
* [connected]
* 424.971568ms

If you are having trouble please file a GitHub issue at
https://github.com/exercism/exercism.io/issues and include
this information.
```