Connectors not selectable after centre of diagram

[Andy]

I have a diagram with many shapes linked with dynamic connectors. If I
select everything on the diagram and centre it, I get some connectors
that are no longer selectable.

Some of the connectors appear to be just slightly off alignment with
the grid. If I select a shape connected to one end of the connector and
move it slightly, a small kink appears in the line. If i move it
further, then a gap appears until visio is forced to repaint using
ctrl-alt-g.

I have also tried a spatial search at points where the connector should
be and this does not return anything for the connector, until it is
forced to align with the grid.

Thanks in advance

 

[Andy]

Some further info, where i have lines that are U shaped, but with
different length legs, the line bounded by a box enclosing the shorter
leg is not selectable, but the section of the longer leg is.

This section of { |
line is selectable { |
| | <- Everything
|-----------------------------| below isnt