Why does iCloud delete my music?

Using Apple Music, I have iCloud Music Library enabled on my iPod Touch as well as iTunes. Since doing this I have found that thousands of my tunes have been deleted. Why is iCloud doing this? All missing tunes were purchased from the iTunes Music Store. I can re-download them but there is no way for me to know that they are gone until I try to play them. I have tens of thousands of tunes, and going through all of them to find the missing ones is a nightmare. I have re-downloaded about 1,000 tunes so far. This has taken me dozens of hours to find them and download them. I'm worried that iCloud will find them and delete them again.

How to stop iCloud from deleting my music?

Please, please help! Thank you for your advice!