Miller cleared waivers and was assigned outright to the Cubs' alternate training site, Jordan Bastian of MLB.com reports.
Miller was designated for assignment by the Cubs on Monday.
Miller was optioned to the Cubs' alternate training site Tuesday, Jordan Bastian of MLB.com reports.
Miller had his contract selected by the Cubs and was added to the major-league roster Sunday.
Miller will be a part of the Cubs' 60-man player pool this season.
Miller is one of several candidates for the Cubs' final roster spot out of spring training, Gordon Wittenmyer of the Chicago Sun-Times reports.
Miller went 2-for-3 with a double and a run scored in Thursday's Cactus League game against the Rangers.
Miller signed a minor-league deal with the Cubs on Wednesday, Ken Rosenthal of The Athletic reports.
Miller was outrighted off the 40-man roster, the Minneapolis Star Tribune reports.
Miller had his contract selected by the Twins on Sunday.