Up/Down does not work in 735xt

Forerunner 735XT (software version 7.10)

Problem similar to this one:
https://forums.garmin.com/showthread.php?366747-BehaviorDelegate-onBack-is-not-called-when-progress-bar-is-active-on-fr735xt

But it is for regular view:
class TestingAppView extends Ui.View
class TestingAppDelegate extends Ui.BehaviorDelegate

This code works in simulator (source in attachments)...
function onKeyPressed(event) {
// Skip
var key = event.getKey();
if (key != Ui.KEY_UP && key != Ui.KEY_DOWN) {

return true;
}

// Key
App.getApp().data.setMessage(key.toString());

Ui.requestUpdate();

return false;
}

But does not work in real device.
Back does not work in progress and up/down does not work in usual views (delegates).

So we cannot use watches for our purposes (communication with phone).
It is mission critical issues for us!