It is funny, but after update of the app I have the same problem. Now I, ve tried the following steps and it helps:
1) Go to Google play on your watch,
2) Select the top left tab “My Apps”
3) Tap on the Tag Heuer connected App
4) select “set the watch face” tab (I have Russian language, so the tab name may differ)
After this the app downloads TH watch face. And then in my case the mobile app begins to work.
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