I have the same issue with Ultra after the latest FW update. It happend to me 3 times already. Yesterday evening it happend while I was normaly wearing it, I am not aware of any ongoing sync with one of those apps. I was unable to connect my watch with cable as I didn’t have any with me. There is alwas arrow and two dots blinking on the screen and no combination of holding buttons doesn’t help.
However, this morning it recovered itself and for now it seems that it works.
I am becoming very frustrated as my Spartans are not reliable anymore. And there is no info about the fix. I have a race next week and I am affraid it could happening just before start. This is a very bad bug for me:)