While @Raiklin said Pence needs to send letter to Governors/States today, I do not see a letter from Pence is critical informing Governors/States.
In all of the contested states, there are either ongoing legal battles and/or State Legislatures holding hearings. They know their states have issues. Pence pointing it out is not critical.
Sending a letter today is showing your hand, IMO, and giving the enemy time to come up with a stronger defense.
06 Jan is the day that matters. Pence can bring up ongoing court cases, State Legislature issues, etc on that day and not count those votes due to ongoing and/or unresolved issues.
My take. Not a Constitutional lawyer like @Raiklin.
Just an Anon.