PBIX files with data model

Hi Folks,

We have about ~10 workspaces with various reports created by different business users. When I was downloading pbix files of these reports, some reports are using PBI service (live connection) which is fine, but some reports for some reasons contain data model in the pbix files. When I was trying to re-connect these reports to PBI service, it says "The Connect live option for this file is disabled because it already contains data from another data source.......".

My question is how were these reports created in the first place? How can we fix this?

Thanks.