Why does my link straighten out?

I have a link that gets drawn in a way that I like at the time that it’s first drawn. If I touch its “from” node and move it slightly, the link reverts to a straight line, which I don’t want. It never seems to return to its original form, even when I place the node again at its original location. How can I maintain that original link path?

Here’s a fiddle with an example: gojs semi-hidden links - JSFiddle - Code Playground

To reproduce, move the “six” node slightly and watch the magenta link go straight.

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Set Link.adjusting to some value other than the default of go.Link.None.