Sanches suffered a setback during Swansea's FA Cup tie against Notts County last month, and since then has been sidelined with injury.
Bayern boss Jupp Heynckes openly admitted that Sanches had returned to get treatment and insisted that despite being on-loan at Swansea, that the midfielder is a 'very important man', as reported by ESPN.
"He is a very important man, and it's no secret that he is here," Heynckes told a news conference. "He is getting treatment from Dr. Muller-Wohlfahrt.
"Hasan Salihamidzic [Bayern's sporting director] is in constant contact with the player and his adviser. He still belongs to Bayern."
Meanwhile, Swans boss Carlos Carvalhal has stated that he expects the Portuguese international to be back to full fitness sometime next month, as quoted by the club's official website.
"In the beginning they said it could be long term, but I believe he will come back next month," Carvalhal said. "That's my feeling. I think he will be back sooner than we expect."
Sanches hasn't had the greatest time in England so far, and due to his poor form and string on recent injuries the midfielder could miss out on a seat on Portugal's plane to the World Cup in the summer.