If a cell is empty, it does not exist at all, presumably as a performance optimization. This also means that if you at any point delete/erase all the pixels in a linked cel, the cels will all be deleted (and unlinked).
Currently, you have to draw one cel first, and then link it to your empty cells to make them non-empty.
I agree, it would be nice to be able to link empty cels, and to have those links persist even after the cels are made empty.
The timeline could look like this:
Could we have this moved to Features?