- Wait for the GPS fix and be sure to have at least a 15m precision (otherwise you won't be able to save the HN).
- Insert all the requested information (some of them are required just once and you can set them from the menu) and press the big button "Store HN".
Regardless of whether the precision of my position is green 6.0m, 8.0m or 12.0m, or red 16+m, the StoreHN button is just very briefly flashing in a 1 second rhythm. Simultaneously, the phone's GPS symbol in the upper Android notification area is disappearing, appearing, disappearing... Switching to any other GPS app causes the symbols to be displayed constantly, after a switch back to HNH the symbol goes back to dance.
Both City and Street seems to be filled in correctly.
When trying hard and fast to repeatedly press the StoreHN button, I've possibly succeeded twice to press it, the button changed its color to blue. But no HN got stored. On one such attempt the app crashed.
Could the 15m requirement be loosened to 20m? Or a user preference for it? I can imagine being unable to get a good position precision on some places with e.g. dense and tall buildings, or with suboptimal constellations of satellites.