If you're one of the lucky few to get the newest Android on your device, you might notice some apps behaving oddly. This may be due to certain apps not requesting permissions when they need to, causing them to break.
In Android 6.0, Google has implemented a new permission system that requires apps to request access to things like your camera or location individually, rather than in one bulk permissions grab when you first install an app. You can also disable permissions one at a time later, if you change your mind. This is a good change (and one iOS users should be familiar with), as it makes it much easier to protect your privacy.
The problem, however, is that apps need to update themselves to actually ask for those permissions. If a developer decides to update the app to "support" Marshmallow by targeting the new version, but doesn't add dialog boxes to request individual permissions, that app won't get those permissions.
This can lead to some broken features. Curiously, Google's own Google+ app is one such example. When creating a post, users can't see thumbnails for their recent pictures until they grant the Storage permission. Otherwise, parts of the app's interface simply won't appear.
If an app isn't behaving the way it did prior to an update, you can check its permissions and see what it's allowed to do. Head to Settings > Apps > [Name of the app] > Permissions to see what's enabled and what's not.