The rumours about a failed medical weren't completely false. They found an anomaly on his knee. They conducted more tests and apparently they are either.
Mulling over whether to conclude the deal. Or
Lyon are just waiting till the window opens to include his sale in this year's accounts rather than last year's.
This is turning into a saga.
Neither club has indicated the reason for the delay so you can't be completely sure that it is due to the player's medical.