If the logbook is presenting the fields on the desktop site but is not showing these within the mobile app you will need to check to see if you have a format validator field as an option.
This will require an expression to be used in order for this to action within the logbook.
If you have no expression within this field set up you can use a text field instead. This should then show the fields as expected within the logbook on the mobile app.
If the above does not help and you are still facing a blank logbook on the mobile app raise a new case referencing this article with the below information:
Logbook name.
If this has ever worked previously.
Provide system access.
App version.
Device make/ model.
Operating system/ version.