I bought Halo explicitly for split screen co op play on Xbox 1, as I come to discover matchmaking makes it impossible to play on the same team together even though you are playing on the same screen. This must be a glitch in the coding. Time and time again I tried and found my friend and I put on opposing teams, with no luck as to ever play together. Please fix this as this is what makes Halo so fun to play!
On a side note, I would also prefer the option to split the screen horizontal or vertical, as opposed to having no choice.
This is one of the many things they are working on to fix!