Nobody knows exactly what’s happening, but according to this thread on Google’s forums, removing Android Auto 6.1, clearing the cache and the data, and then installing an older version of the app brings things back to normal.
Of course, this only happens for a limited time, as the speedometer in Waze then goes away automatically when the latest version of Android Auto is automatically installed.
“Tried to revert to a previous version of AA, but it doesn’t fix it. The solution is to delete data in AA, in this way the speedometer comes up again, but if you disconnect and reconnect the phone the problem appears again,” one user explains on the forums.
The good news is the issue has already been forwarded to the Android Auto team, according to a community specialist on Google’s discussion forums, but for the time being, there’s obviously no ETA as to when a fix could land.
On the other hand, it’s important to emphasize this isn’t a widespread problem, so it isn’t happening to everybody, but at the same time, it’s also not clear who is impacted and who isn’t. As others have mentioned on the forums, if you too come across this problem, the easiest workaround is to go back to an older Android Auto version, though this resolves the whole thing only temporarily, or to simply stick with Waze on your mobile device without connecting it to the head unit.
Android Auto 6.1 and the previous versions (for a downgrade) can be found on this page.