While both parties are eager to see a transfer agreed, a change of agents means nothing can be formally negotiated for another month.
BILD says it won't be April until Sane's new agents are clear to speak with Bayern on his behalf.
Meanwhile, the Germany attacker made a successful playing return with City's U23 team yesterday against Arsenal. It was the first time he's played since suffering a knee injury in the Community Shield at the start of the season.
City manager Pep Guardiola said on Friday: “It is unbelievable that the players of the first team can participate in the games of the academy for their return. It's good."