Where are you running these sources from? I'm assuming that since you're talking about a PLAYBAR, what's driving the sound is a TV set, but are these "smart apps" on the TV, or from another device?
Generally speaking, when you have one source that works, and others that don't, you've likely got an issue with the audio settings for each app/device not set up to send Dolby Digital. My guess is these apps are sending either Dolby Digital Plus, or DTS, neither of which can be read by the PLAYBAR (well, Sonos software in general).
Double check what each app's/device's audio settings are, and lock them down to Dolby Digital.
Bruce