You just know I am going to start with the obligatory, "Why on Earth are they using IE?" It is old and broken and insecure... I assume there is some Silverlight requirement in play such that the client cannot standardize on Chrome or Firefox?
Speaking of Firefox, how does DocuWare perform on Firefox and Chrome? Edge? Edge would be the heir apparent to IE, though I think it was pretty much created new from the ground up. It would be interesting to see how they all perform relative to each other.
Sorry I cannot be of more help -- we are on 6.11 and all browsers seem to work OK. We have to use IE for things like setting up Import Configs, since that is still in Silverlight in version 6.11.