I experienced the same issue as you had back 2016, but I don't find efile center under support. Is 2018 ATX is different from 2016? I did Synchronized efiles with EFC, it did not correct the problem. Any help will be greatly appreciated.
I e-file a 1120. After transmitted in return manager it says E-file has been rejected by our processing center. status show transmitted to EFC. Where can I find out the reason for rejecting? Thanks all in advance.