Your problem appears to be the same issue that has been discussed many times. If you "Trim" the derailleur in any other gear than the highest gear "smallest tooth gear, The software thinks that the lowest gear is the highest. You have to put your shift pod into trim mode and manually (in very small increments) move the derailleur all the way down into the smallest cog, then take it out of trim mode and use your app to shift back up into your highest gear. I have accidentally done this enough times that I finally learned not to do what you somehow accomplished.
As a bit of history. In the first versions of the App, one had to trim each cog manually, and the App did not have the cog tuning for each gear. When they updated the software, it appears that they never put any warning is their manuals not to try to use the shift pod in trim mode in any other gear than the smallest cog.
Good luck