We get MFMDS032E-FIND error RC=004 REASON=008 while trying to use drag and drop to transfer a file from the PC to PDSE on the mainframe.

The error message means: PDSE member's share options do not allow you to access it. This can occur if the PDSE is shared by multiple users and while one user is attempting to use drag and drop to transfer a PDSE member another user has opened the same PDSE for update in a different partition. To correct this error make sure only one user is updating the PDSE or change the share options.