The Serie A giant allowed Ricardo Rodriguez to depart for PSV earlier in the week and looked to have identified a replacement in the form of United States international Robinson.
The 22-year-old, who joined Wigan from Everton last July following a successful loan spell, had appeared set to provide cover for Theo Hernandez.
But Milan has instead recalled Diego Laxalt from a loan with Torino.
Wigan released a statement confirming Robinson was heading back to DW Stadium after a hitch in the transfer.
A fee was agreed — reportedly worth up to €11.9 million ($19.4 million)) — and Robinson travelled to Milan earlier in the day, but the need for additional tests after a medical meant the deal could not be completed before the transfer deadline.
Milan had also been linked with a move for Matias Vina from Nacional in Uruguay, but he joined Palmeiras.