Copy and Paste Error RSEG1270E

I have created filters for two source physical files (QLBLSRC, QCLSRC). I
can right-click on a source member (*.cbl or *.clp), choose Copy, and then
right-click on the COBOL source physical file (QLBLSRC.file.pf-src) and
choose Paste. This lets me copy files into the source physical file.
However, I cannot do the same for the CL source physical file
(QCLSRC.file.pf38-src). A message window comes up with error RSEG1270E
Invalid Drag and Drop Operation. 

I suspect this may have something to do with a difference in source files.
The source file that lets me copy has a *.file.pf-src extension. The source
file that does not let me copy has a *.file.pf38-src extension. But maybe
this has nothing to do with it...

Any ideas on what is causing this problem and how I can correct or work
around it?

By the way-
I was moving a source member from one source physical file to another.
(Right-click choose Move.)  I selected a source physical file from the tree
that appeared. However, when the window came up with the CPYF statement in
it, I changed my mind and decided not to move the member into that
particular source physical file.  I clicked the cancel button. This caused
the source member to be completely wiped off the iSeries. Just gone.
Fortunately it was a small CL program and easily recoded.

This does not appear to be a bug. The WDSCi iSeries Command Log view showed
a RMVM command being the last command executed.  It appears that either: (1)
the RMVM executes before ensuring the CPYF command has finished, or (2) the
RMVM command executes after cancelling the CPYF command. This resulted in
the loss of the member. Might be good to eliminate the cancel option on the
CPYF command or ensure the CPYF executes before running the RMVM command. 

Thanks,
Kelly