Can't e-file because of forms that can't be efiled

I'm trying to e-file and getting a message that says I can't efile because the return has forms that cannot be efiled. It's a pretty basic return with the following forms: 1040, Schedule 1, Schedule 2, Schedule C, Schedule SE and form 8995. I've efiled in the past with basically the same forms. Any idea why this won't work? I can't find anything on the IRS website that answers this question. Thanks in advance!