I have a master component, Table, that is composed of two smaller components, _TableCell and _TableHeader. The _ naming convention that prevents them from being exported.
I published everything in the file, then cut the group and pasted it into a new file, and republished.
Now the _TableCell and _TableHeader components have lost their connection. I think I understand why, but damn, wish the Figma documentation made it more clear that helper components with _ naming are gonna get lost.