Wizards of the Coast (WotC) announced today Collector Boosters and the Commander Decks for The Lost Caverns of Ixalan have been delayed due to production issues.
Most locations will not receive Collector Boosters by November 10 and stores should not expect to have them in time for The Lost Caverns of Ixalan prerelease events. WotC anticipates Collector Boosters will begin arriving at stores during the week of prerelease and up to three weeks thereafter.
The Lost Caverns of Ixalan Commander Decks will have limited availability during prerelease in North America with more availability expected following the release on November 17.
Read the official announcement from WotC.