Adobe request for signature freezes on Adobe DC

Hi all,
We have a user who uses Adobe sign daily to request for signatures with multiple drawings through the day. It is a critical operation.

We find that the request for signature feature freezes allot on Adobe DC. DC is up to date according to creative cloud; the Windows OS is up to date and we have completed a re install and repair installation.

The problem is not that the request for signature feature does not work, it is that on certain documents, no matter what we try, we can just not request for signatures on.
We have tried different documents and they do work. Nothing in common with the documents that don't work, no specific time, just random. We just leave it for a day or two and magically, the document can request for signature.

What happens is that we click request for signatures, enter the signers email address, and proceed to the page where we need to add the blocks to add the signatures, but nothing happens, the document is just frozen. Can't scroll, zoom or do anything in the window itself, but everything to do with Adobe DC, such as menus and toolboxes work. So hence the feeling that it has something to do with the adobe sign and not the DC application itself.

Are there any troubleshooting articles that one could fund help or technical documentation to understand how Adobe Sign works and what services it relies on? 

Help is appreciated. Thanks