Halo reach is missing in Mcc

I bought halo mcc xbox one dics. I played it all the campaigns. But recenlty my halo reach is missing. When i click resume on halo reach, it says ‘dlc required’. So i went to manage game & add-ons, it is still there. So open halowaypoint to research for solution. I have tried restart my xbox, hard restart, clear cache and lastly uninstall the game & reinstall. But when i reinstall it, Now my halo reach is missing. Only halo 3 odst was there. I went to xbox store, find halo reach and its says i need to buy it again. After that i went to xbox support but ‘We’re experiencing heavy volume right now’. Please help?! Why i need to buy again halo reach but i have already bought & play it on xbox one.