The main problem is that that you have to reset the unit before each use, which, while in itself is not a big drama, but then is stupid, if you grade has no small pen is available to press the reset button (because, for example, . degree is traveling).
After the various posts here I also have the support of Ultra Sport contacted and get a very bland statement, with a useless link regarding problems with the older Nexus 4 and yet very questionable statement:
"Unless your smartphone model but Bluetooth 4.0 support, use the correct version of Android and the right app, the problem may not lie on the chest itself."
The only Bluetooth device that makes problems, is this chest, but LT Support "can not lie on the chest itself the problem." Eh clear. Apparently, quality assurance at the highest level, if not even the Google Android reference models of work with it ...
Update May 10:
I'm sick of it now and send the item back. Today I used a whole half an hour, until I managed to get transferred from the chest strap values, regardless of which app I've tried.