Need help understanding this error for Offline Areas

[LayerItOn]

Hello,

I have a field map project that has been used offline for over a year. Now I checked it and notice this error message. Can someone explain what it means and what I should do? 

Thank you in advance for your help! 

[LayerItOn]

@DanielFox1 I was able to remove the index in ArcGIS Pro, but now no new offline areas are packaging even though the error messages are not present. 

[DanielFox1]

Are all your layers still in the same projection and same projection as the basemap?

Do you have Global IDs, one layer is editable, sync enabled?

Have you tried to rebuild the spatial indexes?

Do the field indexes still exist?