Having the exact same problem. Reinstalled the app and still nothing. 

@OuterLimit I have the same problem.  In my case there is a small leakage current on the traveler that keeps the small LED buld that is being controlled very dimly lit.  It seems to be enough current however, for the switch to think the light is ON.  (I've deduced the only way for the HS-210 to know if the light is off or on is to measure the current in its two travelers since it can't know the state of the other 3-way switch.  Current flowing = ON, No current flowing = OFF).   Looking for a fix.  None of my other HS-210's seem to have that problem with LED lights.

@OuterLimit I also had the same problem in the original post.  I had a 3-way / 4-way / 3-way circuit.  I replaced the 3-way switch on the line side, but it would always think the light was off.  I tried swapping out the smart switch, but the other one behaved the same.  Once I replaced the second 3-way switch with the other smart switch, it was properly detecting the status of the light.  Even flipping the dummy 4-way switch will toggle the status correctly.  I was under the impression that you only needed one smart switch, but I was only able to get it to work with both.

@keifer 

Appreciate the reply and ended up with the same solution. Once I added the second switch all was good. Only thing I could think was a dumb motion sensor sharing the common line leaking power. 
 

Few days later did another room with a four way (no motion sensor) and everything worked great with a single 210.