Copying fields sometimes doesn't copy their content. But when?

[David Epstein]

Is there some rule that determines whether, when a field or group is  
copied in LiveCode (using the "copy <object> to <somewhere>" command)  
the contents of the field or grouped fields are copied?

This result seems strange:  copying a field or group from a different  
stack to the current card includes the field contents if the current  
card is card number 1, but not otherwise.

Recipe:

Create two stacks, "x" and "y"
Create a second card in stack y
Create two fields on card 1 of stack x, put some content in them, and  
group them.

Now with card 1 of stack y frontmost, type in the message box:

copy group 1 of stack "x" to this card

Then with card 2 of stack y frontmost, type in the message box:

copy group 1 of stack "x" to this card

Result:
When copying to card 1, the content of the fields is copied.
When copying to card 2, the fields are empty.

Thanks for any insights into this.

David Epstein