Sometimes a Secure Note get emptied. This happened once when I was editing the note, but unable to save (maybe due to connection problems). I tried to save the note several times, got an error every time. When I quit editing mode without saving, all the note's content had disappeared.
Since item history is not available in the Android app, there was no way to recover the contents of the note in the app. I had to log in to 1Password on a computer. From the item history it seemed like I had deleted all the contents of the note and then saved it (I did neither of this).
A couple of days later, another family member wanted to open the same note (long after I had recovered it and some problem-free edits later). It was empty when they opened it. They did not try to edit the note. I recovered the contents again from item history, and again it seemed like this family member had saved a new and empty version of the note, but the note was empty when they opened it.
I try to include all relevant details and hope it will help you figure out the problem. I am confident it did not happen due to an user error. It is a note in a vault shared by two family members. It contains a simple list of about 20 to 30 lines. I have only had the problem when viewing/editing this particular note in the Android app (but I have not edited noted extensively in the app either). I did not look at app log when it happened; I will if it happens again.
I was planning to buy a family subscription for my family, but this makes me worry that password entries could get emptied in the same fashion. I am able to use the item history to revert to the previous version (although it is a major inconvenience without this feature in the Android app), but other family members will not.
(NB: I use the beta version of the app, but the family member uses the latest stable version.)
1Password Version: 7.1.BETA-5
Extension Version: Not Provided
OS Version: Android 8.1.0
Sync Type: 1Password account