There was a recent update to the classic app (version 2.17.0 to 2.18.0) that caused a lot of people to have issues with presence, app crashing, and missing device icons. Another update with some patches that fixed the presence and crashing issues (but not the icon issue) was released for Android recently (2.18.1), but I’m not sure about the status of the iOS update. You might check your app version, and also see if there’s an update available in the app store.
There are several threads about this issue, here’s one: