I changed my employer address last night in the business area and verified that the 1099-NEC generated was correct, but waited until today to electronically file it. Well, somehow it reverted to the old address and I didn't catch it until I printed the forms. It's still pending being accepted. What do I do now? Is that even a big thing?
You've already filed the return. It will effect any correspondence the service sends to you between now and the time when you file your next tax return.
If you are going to file a business tax return in the next month or two then you may not need to worry about it. Just change the address on your business tax return and it will change it with the service. If there is no correspondence sent between now and the time that you file that return then it will not matter.
If you are going to take any longer to file your business return then you may want to file form 8822-B and change your address with the service in case they are trying to reach you. The information about that form is here.