Was this resolved for you? I'm having the same problems too. Workspace some times let the users submit form and doesn't carry data.
I'm not sure how they run the latest versions without making it compatible with the existing applications.
Any help is highly appreciated.
No, it has not been resolved. Right now we are neck deep in developing an LC project so more research on our end has been put on-hold; I posted this here hoping that someone had encountered the same issue, or that perhaps someone from Adobe would see this and could get us the information we need.
For the user in question we had them uninstall DC and reinstall XI. Our agency has a policy of keeping pretty up-to-date with various versions so I know we are going to have to address this further at some point in the near future, but we haven't gotten there yet.
I've noticed similar situations where Adobe Reader DC will not properly apply Reader Extensions to an enabled form. I've also seen issues with Adobe Reader DC not printing properly from the Reader plugin.