They should eventually show up again for you.

Thanks~

Thanks everyone! It really got me frustrated. But I'm glad I could find the answer!

I have all the coral, turtle shells, & feathers. I only have 6 pieces of the tablet. I finished with the rubble yesterday. I have not had any tablet pieces show up since my rubble was at 22%-ish. It's been almost 24 hours since I completed the rubble and have had plenty of the collectables that I've finished & mushrooms. I have not seen any tablet pieces. I really want to finish it

I haven't had any tablet pieces since my rubble was cleared either, and that's been a few RL days now. Had plenty of everything else, but even sitting watching the rocks didn't yield tablets heh.

After my rubble was cleared, I still found a couple tablet pieces but it took a long time for them to show up.

Do the tablet pieces show up only near the rubble or all over the island?

Only near the rubble, and far less frequently than the other collectibles. Each tablet piece will stop appearing once you have collected it. When the entire tablet is recovered, there will be no more tablet pieces.