Sorry for the very slow response and very sorry to hear that this is happening! We are not sure what exactly is happening, we haven’t had any other reports of this. Let us know if you still have this issue, or managed to work around it some way!
Our next app update will include a feature to detect crashes, and will automatically backup your pins, and other favorites data, so that if you have to re-install the app, you can recover your data exactly. We hope to have this update available in the next few weeks.
For now you could try the Settings > Export feature. CSV export works best for pins, GPX for routes/tracks, though GPX is a less rich format than what PocketEarth uses internally, so re-importing GPX files will loose some details. Doing a GPX export of each track/route individually will re-import better than the single Settings > Export > GPX option.