Not being a slave to electronic filing, it took me less than half an hour to print them out and mail them in yesterday.  Fortunately my state doesn't require a separate form if the federal extension is filed and no tax is owed.  (Rare to see tax owed on those March 15 extensions for S corps.)

My problem was transferring them from 2023 to 2024.  They were in the 2023 data files, but 2024 didn't recognize them.  I had to open 2023; open the returns; and save them under a different name.  This happened with a few individual returns, earlier this year.  Technology is never perfect.