I'm pretty sure this is a bug within Visio but I can't figure out how to re-create it... or avoid it.
I have a tool that reads the direction of an arrow in Visio by looking at the "BeginArrow" and "EndArrow" cells in the ShapeSheet and it has worked great. However, a user was having issues with the software correctly detecting direction and I quickly realized why.
The Issue:
There are arrows with an arrowhead at the beginning or end but whose shapesheet has a value of 0 for each. If I simply edit the shapesheet cell that has a 0 and replace it with a 0, the arrowhead disappears so the arrow and shape sheet are back in sync. Similarly, if I change the arrow head and then change it back to what it was, the shape sheet no longer says 0 for the arrowhead.
Has anyone run into this issue before and figured out the cause?
Things I've tried: I have tried copying and pasting arrows from other documents, copy-pasting from documents in another instance of Visio, dragging the arrows from other documents/instances of Visio, asked what the user did to create the arrows and it wasn't anything I hadn't tried to so I'm at a loss.
AFAK, this sort of odd things in Visio are usually version upgrade bugs. The "problematic" diagram may have been simply created in some previous version of Visio. So in a previous version of Visio that "broken" diagram may even still work properly. No software on this planet is free of glitches anyways; normally this sort of issues can be easily fixed by saving to VDX/VSDX (i.e. xml) format and then opening it and saving back to binary format.