internal storage – I can’t access some music folders via music player, other works fine

I have several GB of music in several folders on internal storage. When I want to play it with (any) music player, some folders play fine, some shows that there is no music, despite it is.

Same happen with pictures, via file explorer I can see them, but via gallery app only few of them.

When I do automated storage cleaning, some of these files appeared back to be able to see them via applications, but not all.

Can it be, that my internal memory is dying ? The phone has 4 years, extensively used LG v30

Thank you!