The nine-year-old provided one of the storied steeplechase's most emotional stories when he won at the Aintree course last year for the father-and-son team of trainer Willie Mullins and jockey Patrick Mullins.
Stablemate I am Maximus, second in 2025, is currently the favourite for this year's edition.
Nick Rockett has only been seen once since reappearing at the Down Royal track, near Lisburn, in Northern Ireland last month.
There was a surprise at Wednesday's declarations when it was announced Patrick Mullins had changed horses to ride Grangeclare West, paving the way for Tom Bellamy to receive an unexpected summons to partner Nick Rockett.
Bailey's joy, however, barely lasted 24 hours, with Nick Rockett reported to be coughing.
His absence means the first reserve, Gordon Elliott's Pied Piper, will come into the four-mile race, featuring 30 fences.