Hi all, thanks for your patience. We weren't able to replicate this, but I got some feedback. 

Check out this article under "How to amend a previously amended return": Amending an individual return (1040X) in ProSeries Review step 19, check the "check this box to file another federal amended return electronically" box. By doing so, it clears out the electronic filing status from completed to ready.  

If you're still having trouble, please contact us to sanitize a client file in ProSeries and we have a closer look: 800-434-6818.