Just to follow up, problem solved! I mentioned mod_sec settings for my server as being the possible culprit as suggested and they were able to fix this issue. Here's what the tech agent said to tell them when you go to support:
Just let them know you need the rule 340163 whitelisted for domain.com as its hitting a mod_sec rule.
Apparently you will need to do this for each domain that is having the issue, but it works. Thanks for all the suggestions everyone!