Sorry, I'll have to ask one more dumb question. Your Kwikset 910 is ZigBee correct? I have not seen the error you are experiencing. Unfortunately, I do not own a Kwikset lock to test with. I know others are using Kwikset and this DTH successfully. If possible could you PM me with your live logs after creating (or updating) a code. I'd like to see where the disconnect is.
The error you are showing means the lock manager app is sending a code, but the lock itself is not reporting that it was set. Therefore, the manager keeps trying to send the command to set the lock code. I'll also try some additional testing with the lock I have.
Also to note, it seems that there may be several users experiencing this issue based on comments in the Lock Manager App thread. They use a different DTH, but in any case we'll get to the bottom of it.