UEFA have released the following statement.
Following a technical problem with the software of an external service provider that instructs the officials as to which teams are eligible to play each other, a material error occurred in the draw for the UEFA Champions League Round of 16.
As a result of this, the draw has been declared void and will be entirely redone at 15.00 CET today, Monday 13 December 2021.
The draw will be streamed live on uefa.com.
We apologise for the inconvenience this may have caused.