Strange problem when filling in data fields ???

Hello
I am facing a strange problem when filling in data fields, please see attached video.
I create an array that consists of several data fields separated by a dash. 
I can handle all data fields and fill in the data fields with the copy data field tool, except the last data field in the array.
If I add a additional data field to this array the problem "shifts" to the last data field an so forth..... if adding another data field!
If at the end of the line, after the last data field, I add a character like a dash everything works perfectly.

Gridlock and Snaplocks are off.

What happens here .....?

I need urgently help for this issue.

many thanks

Regard

Raphael