Hi @Hoinsk,
Welcome to the community! First check the instances folder of your device’s odk folder you assume data to be missing (from KoBoCollect android app). If you find any files in this instances folder you should know that there are files in your device that can be extracted and synced with KoBoToolbox server. For this, you could simply follow the instructions laid out in the support article Manually uploading submissions.
Have a great day!
