The 25-year-old wrote on X: "I am disappointed and upset about the events of the past few days and the failed transfer to AS Roma.
"Above all, I am very surprised by the supposed reason for the collapsed transfer. Both the doctors of the Austrian Football Association (ÖFB) and the medical department of RC Lens have closely monitored me and regularly examined me over the past years. Most recently, I was thoroughly assessed at the start of pre-season training in Lens and no irregularities were ever found. Therefore, the interpretations of the medical check in Rome are highly perplexing and completely incomprehensible to my team and I.
"I will now discuss my situation with the responsible parties at Lens and at the ÖFB and focus on the tasks ahead."