Hi ,
Since yesterday 5 of my devices become unavilable .
several xiaomi contact sensor
one light switch
one camera (foscam)
The strange thing is that they are still working from the app
for example I can turn the light on or off from the app and the tile status changes .
The same for the contact sensors, When I open the window it changes the tile status to open and close when closing .
So not sure why it’s in unavilable status in ST .
Any Ideas ?
I also had this happen a few days ago.
I unplugged the hub waited a few seconds plugged it back in.
Everything is happy now!
I have the same issue. Recycling hub didn’t help. I have lights that are working but shows unavailable. I think this is app’s device health issue.
Thanks ,
Will try that tonight and update .
Login to https://account.smartthings.com and see what it says there for the status of the devices.
I had all my presence sensors and a power switch go “Unhealthy” as well. They all are working fine but permanently prescribed with a red dot no matter what I do to them.
Think really hard what you changed. Did you move the hub, add something to the area where the hub is? I was getting the same exact thing every night. I couldnt figure out why things were going offline only at night. I thought it was the kids ipads or something interfering. Finally it was my apple TV device. The thing was next to my smart things hub and causing interfere. I move it to the other side of the cabinet and no issues.
Thanks everyone for helping .
All my devices but one returned to Normal without me doing anything , not sure what happened .
One was stauch at some status (roller shutter) but stopping electriciy and starting after several sconds did the trcick 
Thanks again 