I am running some SHRINKFILE operations to clean up a bunch of tiny, unnecessary files in a filegroup. For one of the shrinks, the command below results in an error:

DBCC SHRINKFILE (N'myfile' , EMPTYFILE)'

File ID x of database ID x cannot be shrunk as it is either being shrunk by another process or is empty

It is not empty nor being shrunk. It is being run on a database not currently in use by anyone except myself.

On SQLServerCentral, a thread from a decade ago suggests adding a few MB to the file because that "resets an internal counter or switch that tells it it's not in the middle of a shrink now."

This worked - awesome. But can anyone explain with greater detail how/why this works in regard to SQL Server internals?