Google has announced that the in-car Bluetooth audio issues that some users updating their devices to Android 7.1.1 Nougat were facing have been resolved. According to Google representatives on the issue tracker for the bug in question, Google has managed to squash it in their lab testing, and should be issuing a patch to users that will fix it in the near future. The representative, posting under the handle of amruthav on the issue tracking forum, did not state exactly when Google will be rolling out this fix, only saying that the patch "will be available in a future build". This means, for now, users will still have to deal with the problem. Google normally puts out Android security updates near the beginning of a given month, so this fix may well end up in that patch.
The issue in question is an inability to stay connected to in-car Bluetooth systems, reported by multiple Huawei Nexus 6P, Google Pixel, and Google Pixel XL owners who had updated to Google's latest Android 7.1.1 Nougat build with the build number NPF10C . Users reported that their device would connect to a vehicle's built-in Bluetooth systems without much issue, but would then disconnect a few seconds later with no warning, error message, or indication as to why it was happening. Users indicated that the issue seemed to only affect vehicle systems, leaving Bluetooth audio capabilities with devices like speakers and headphones perfectly intact. The fairly widespread issue affected a large number of users, garnering 161 posts on the Google bug tracking forum alone.
For now, there is no known workaround for this issue. Users in various places like Google's bug tracker, the Nexus help forums, and XDA Developers have been told to do things like boot their device into safe mode, clear their device's cache, or perform a factory reset, but thus far no solution seems to be working consistently for all of the users that try it. Scattered crops of users are reporting success with factory resets, but this seems to be the exception, rather than the rule. The issue is not affecting all users, with some reporting their in-car Bluetooth working fine from the get-go. In any case, those affected by the mysterious issue will simply have to wait for Google to roll out a patch.