According to El Mundo, the Electoral Board have argued that Marcelo could travel on the morning of the game. However, this may not be permitted due to coronavirus regulations. Real and the player's representatives are said to be negotiating but no agreement has been reached yet, leaving the left-back in limbo.
The blow is the latest in what has been a frustrating season for Marcelo. A string of muscle injuries have restricted him to just 16 appearances in all competitions and he only started the first leg due to Ferland Mendy's injury.
The draw for the polling station was held at the start of April, with those chosen given seven days to justify being excused from duty. That period has now passed, meaning a separate agreement will need to be reached.