Container jumps to another position when linking with external data

[Kranich]

Hey guys,

I'm new to this forum, as I just started to work with visio. I hope this is the correct section for my question.

I created a mastershape, containing a single container and some other rectangles. The mastershape has shape-data-fields description1 and description2.
There's an excel file, included in the external data section with those columns as well.

I've placed a mastershape on my page, selected this shape, selected the regarding line in the external data tab, rightclick -> connect to selected shapes. Trying this results in a position change of the shape. Another effect can be observed:
Is the shape located inside another container, the container's size expands a lot when connecting those external data.

Does anybody of you has a clue what I can do to get rid of this behaviour?

Many thanks in advance!
Kai