the material linker docs [www.sidefx.com] say to hover over a Rule card and click the red X to delete a rule. But nothing appears when i hover over a rule card. Why does it hate me?

Also is there any rhyme or reason to a material linker deciding to delete all the entries? I'd only been playing with it for 30 minutes and to see that happen did not insipire confidence

There seems to be a bug showing the icon, I can click and delete the card.

I'm not sure we've ever seen the linker delete any materials automatically. By default it is set to Filter Based on Selection, but if you turn that off, do they come back? If not, try logging a separate bug for that one too. Thanks!