When I copy a dynamic block, and then adjust one of the copies or the original, the other copies often get messed up/destroyed--odd shifts in the handles, lines moving out of kilter, etc. Annoying.
Perhaps the following is the cause of the problem: when I copy a dynamic block, Autocad does not give the copy an original Anonymous Name. So I am left with a bunch of blocks with the same Anonymous Name. Perhaps this confuses Autocad.
See example file attached.
Odd. Try this:
1. Copy the instance named "original"
2. Click on the instance named "original" and move the right arrow grip to the right.
You should see the copy get distorted. No? Happens on mine. Vanilla 2012.
When you simply make a copy of a DB, without changing any custom properties, the anonymous name of the copy stays the same as the name of the source (correction: assuming the source DB had at least one custom property). The anonymous name will change after you make a change to at least one custom property of one of the two DBs.
With AutoCAD 2013 I get the same effect you describe. With 2010 I don't get the effect.
Forget the constraints. Unless they are 1000% correct they seam to produce all sorts of problems with geometery, the main problem was that you hadn't included one of the points with a different stretch, and this threw things off. Try the attachment (without any constraints).
Thanks. Yes, I've noticed that the problem does not occur with blocks that contain only linear parameters. Polar parameters also cause big problems.