Missing content and songs purchased through the itunes store.

I've been going through my itunes library, and have been noticing many songs ive purchased in the past couple years are no longer showing as ever being purchased.

I upgraded to a new phone in the last 4 months, my previous iphone 6 still has the songs on its storage. But they've been removed from my current library and purchase history.

Unfortunately I dont have the itunes receipts from 2+ years ago, but the fact there still on my old phone as "purchased" is suspicious.

Makes me concerned as to what else might be missing from the thousands of songs ive purchased over the past decade....

Has anyone else experienced these issues? and if so were you compensated for the missing purchases?