snapshot function doesn't work

I'm have 4 camera's in my account. 2 Stickup battery, 1 stick up plug in and 1 indoor cam plug in. The indoor cam is not showing snapshots, all others do. The protect plus plan is in place. Why does this indoor cam snapshot function not work? Only difference is, that this cam is setup without motion detection, only triggered by other cams. Thank you & best regards Paul