What happens to stocks during the probate process.

My grandfather unfortunately passed in late January. Probate has not started yet, the executor ( my uncle ) has not had the attorney forward me any paperwork to sign. My dad passed several years ago and according to the executor I am to inherit his portion of the estate. I know my grandfather had assets, but not sure how much( very big swings in value from what little I’ve seen) From my understanding the probate process cannot start until I sign some paperwork. Unfortunately the executor still has not given the estate attorney my information so I can sign the paperwork to start the probate process. I don’t have the estate attorney’s information to contact them myself. After that long explanation ( sorry ). What happens with the stocks while this whole mess plays out?