Wizards of the Coast (WotC) announced that “due to logistical issues” Murders at Karlov Manor Bundles will have limited availability for Prerelease events in some North American stores.
No other details were given other than to check with your own local game stores for more information on the availability of the Bundles starting on February 2.
The Murders at Karlov Manor Bundles includes nine Play Boosters, 30 basic lands (10 of which are full-art), a traditional foil Bundle Promo card, and a spindown d20 (with a missing No. 16 as part of a clue for one of the Murders at Karlov Manor puzzles).
Read the original announcement from WotC.