Simply put. I have a symbol library, some symbols are inserted into another library which I keep templates in. I deleted a few symbols but they still show up as symbols in the template library file. I click on Edit in Library and it brings me to the component library but no symbol is selected. How do I fix this? Why is the link not broke when a symbol is deleted?
I have no very concrete solution, but from my experience, nested libraries are a pain in the long run. I tried it for about two years because the support suggested it (to speed up the up- and download flows when working with Sketch Cloud).
But after having constant problems with symbols/components not updating or showing updates even after updating and stuff like this, I switched back and merged everything back into one big library. I have way less problems since then, although the library updates take a few more minutes to show up in the layout files.