P3e / P5 Export function vs Copy (of Schedule) on UDF

I am using P5 and do the weekly backup using the "copy" and "Paste" function.

However, I found out that when I use copy and paste, all the UDF I created in the original schedule are not being copied.

If I was to use the "Export" function, the UDFs are exported to the XER file as expected.

Do anyone come acrosss the same problem ? And if anyone has any explaination on why copy & paste would not work the same way ?

Note : When I do Copy & Paste, all the check boxes are marked for coping.

Any comment will help. Thx.