DataStore object '&1' is in load mode; planning is not possible

What causes this issue?

DataStore object (advanced) '&V1&' is currently in load mode. Data
cannot be changed or created in planning for this DataStore object.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

If you want to change data or create new data, set the status 'Real-Time
Data Target Can be Planned; Data Loading Not Allowed' for the (advanced)
DataStore object.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.