|Not sure I know what you mean by the term "clipping mask" as it relates to Excel.|
When i paste it just copies the values.
Is there an underlying formula, or does the cell have just data?
If there is just data, then Excel will paste the Data.
If there is a formula, then Excel will paste the Formula,
with no data.
If there is a formula, and you want to paste the Data,
then Right Click the mouse, select Paste Special, Values.