ArcGis Pro losing data

[MichaelPorter2]

I am working on a map of a small island in Maine. This map has property lines with first and (sometimes) last dates for each segment. This has been working OK, but lately I notice some property lines have disappeared, and some others have lost attributes.

Reviewing the attribute tabe shows that the lines in question are really gone, or that a particular attribute is missing.

Whatr could be making this happen?

[DavidSolari]

Priority number 1: make sure you're reviewing the data from the source and double-check your layers. I've had panic attacks caused by people adding definition queries behind my back! If it's Enterprise Geodatabase data, see if any missing data is visible in a regular SQL query against the database. For anything on the file system, see if the drive it's stored in has backups, either a full copy system or a shadow copy that you can see by right clicking on the file/folder and selecting "Restore previous versions." Hosted data is the trickiest, check with your admins to see if they've done any backups of the data store, either directly with ESRI backup tools or with full system imaging.

[MichaelVolz]

Do you have backups of the data to compare to see that the data has been lost and also use these backups to recover lost data 

Where is the data being stored?