If you truly want truth you will do the research. If you don’t, nothing I say or show will change your mind.
I have done the research.
That her tomb was empty was reported at the Council of Chalcedon by Juvenal, then bishop of Jerusalem. I am not certain that this fact was known to the church as a whole in the 2nd, 3rd or 4th centuries.
The feast of her assumption has been celebrated even further back than this in Jerusalem, and apparently, what Juvenal reported was well known there.
Any book that you have that says nothing about Juvenal is suspect on this topic, so whatever book you are using isn’t really helpful to this conversation.