Hello,
I tried to update a model from 7.1 to 19.1 and there are some issues.
Some part of objects become invisible(look like hidden in fog) when I rotate the view angle. And all A-connection between objects are disappear.
I guess it's a big gap between 7.1 and 19.1. So I tried to update 7.1 to 7.7 but result the same.