Early Android O adopters will lose some notification controls managing the behavior of their devices, specifically the ability to set Notification Importance that would usually be available in notification settings of individual apps, according to a thread posted in the Issue Tracker of the third developer preview of Android O. The problem stems from Notification Channels, a new functionality that ships with the upcoming build of Google's operating system, allowing users to manage individual categories of notifications by setting sounds, vibration status, icon badge settings, Do Not Disturb overrides, and general importance of those channels on a case-by-case basis. The Alphabet-owned company already said that app developers will have to update their software in order to support the feature, as is the case with the vast majority of other Android O functionalities like adaptive icons. What Google didn't say until now is that failure to optimize one's app for Notification Channels will consequently prevent their users from setting general Notification Importance status of apps.
Refer to the screenshots below for a visual representation of the issue, courtesy of Ron Amadeo of Ars Technica, who also noted how only around five percent of the top 200 currently most popular Android apps on the Google Play Store have already implemented support for Notification Channels, with that figure essentially signaling that dozens of widely used mobile tools will be offered without Notification Importance settings to early adopters of Android O. Seeing how notification priority was introduced as a major feature of Android Nougat, the upcoming release of the operating system will provide a step back in that regard for many early adopters. The Mountain View, California-based tech giant is well-aware of the situation but also doesn't consider it to be a problem, with one of Google's engineers saying that the behavior is "working as intended," with another one of their colleagues elaborating on that sentiment in the aforementioned Android Issue Tracker thread, stating that the System UI Tuner allowing the now-removed functionality was always experimental in nature and is no longer supported in Android O, with some of its capabilities seemingly being absorbed by Notification Channels. A screenshot of the relevant prompt that notified developers of the experimental status of the System UI Tuner can be seen in the gallery below.
Android O is set to receive another, fourth developer preview in early July, presumably by the end of the next week, with the OS itself being scheduled to hit the stable channel at some point in August, so more details on the availability of the thereof are bound to follow shortly.