I saw that Warzone Assault was out for only a few hours and the next day it was gone. Was that a bug? Or does it just release during certain points?
It was actually out for the weekend. It’s rotation is once a month; middle of the month.
Click on the news and search for one labeled “Community Update” Go through it and they announce the exact dates of what modes will rotate in and out. They also post on their twitter when a mode rotates in.