The 7004 is generally available and should be for an initial extension without meeting exceptions, see E-filing Form 7004. Let's look at the little stuff on 7004:

• I am sure you marked initial return in the program but did the program carry it to the 7004, you may need to enter it again in part II, line 5b.
• Initial return - the tax period you marked needs to match what was filed with the EIN.  Double check the EIN year end date and your return  year end date match
• We know the name is the first 4 significant letters. Check the electronic filing worksheet. Look for the name control field. Something irrelevant like The.... may have gotten stuck in there somehow.

Not processed by IRS:

• I have also seen this error when the EIN was very new and not yet in the e-file database.
• It could be the IRS is still processing the 2553 S-corp election.
• In these cases, you may as well mail it in. You can keep trying, the IRS will eventually get it processed.

@jake1