Audio not showing up on posts of me just talking no 2nd audio used.

So I have made 2 posts of me just talking about subjects in my niche today. I didn't use any other sound it it literally just me talking and tiktok is saying that the sound "isn't available"

What is causing this and how do I fix it? It is really annoying me that videos of me just talking say the original sound is "not avaliable."