It is because there is used page at the end which needs to be moved to front of the file.

Please run DBCC SHRINKFILE with NOTRUNCATE option as shown in the following example:

use IEDBNew

go

dbcc shrinkfile(IEDBNew_Data, NOTRUNCATE);

go

dbcc shrinkfile(IEDBNew_Data, 30720) -- 30GB

go