The winds of Pandaria have started to blow in Dragonflight. With the launch of Patch 10.2.7, something changed with Siege of Orgrimmar and made it have a daily lockout instead of weekly.
Other raids, including Pandaria ones, are unaffected.
It is unsure if this is a bug bleeding out from Remix, which starts in less than 10 days, or if this is an intended change. In the meantime, players can use it to farm transmog, mounts, and pets from Siege of Orgrimmar, including the elusive Tusks of Mannoroth and Kor'kron Juggernaut.