Hi Richard,
I see on the Jasper site, they show that IE11 is certified for it, however I do get the same problem when I try using it myself on IE11. Most likely we would need to open a case with Jasper about it which we can do based on a CA Support case. What I would recommend doing is opening a CA Support case, and share that it shows IE11 certified based on this link: TIBCO JasperReports Server Supported Platform Datasheet | Jaspersoft Community
Then we can open an issue with Jasper and find out more.
As a side note I even tested using compatiblity mode and it still didnt seem to work, so it seems like somewhat widespread issue.
Thanks,
Jon I.