If you do not have cell service, the OB1 app has an offline mode. You can set this manually in the settings (slider with "Offline Mode") or set it to the so-called "Auto Offline Mode on Launch" (you can find it directly below in the settings). Then the app starts automatically in offline mode as soon as it does not detect a cell connection. In the OP1 app, it is also possible to download offline maps for the cruising area beforehand and use them offline.
Judging by your screenshot, it doesn't seem to start at all. Is the problem still occurring or more frequently? If so, I would recommend that you open a thread in the
support forum and specify which app version (can be found in the settings under the "Log Out button"), which operating system in which version and what kind of device you are using so that someone can take a look at it.