Nearly a year ago, the Android 11-based OxygenOS11 stable build was released. It made its way to some of the most popular OnePlus phones including the OnePlus 8, OnePlus 7 and the Nord series. OnePlus also stated that it would release the update to the OnePlus 6T and 6T, making Android 11 their third platform update.
Although it took OnePlus a while to resolve a number of issues, the OxygenOS 11. stable build is now available for the OnePlus 6T and 6T. Although this is a good news, WhatsApp becomes unusable due to a bug in the OxygenOS 11 stable build. A family member couldn't download any media from WhatsApp after switching to OxygenOS 11, on the OnePlus 6T. This included older videos and photos stored on the phone. I requested that they back up to Google Drive and uninstall the app.
It wasn't possible. When they attempted to backup their chat history to Drive, it failed. So I suggested that they restart the computer and use the backup from three days earlier. The problem still persists, and they are unable to download media after starting from scratch. This is a known issue with OxygenOS 11, on the OnePlus 6T and 6P. According to several forum threads, it started a few weeks back as more devices switched to OxygenOS 11.
It is unbelievable that a core feature used by WhatsApp has been broken for so long on these devices. OnePlus must address this problem. Although there is no time frame for a solution at this point, I reached out to OnePlus. I will update this post as soon as I have more information.