Windows 10 Keeps changing Internet Explorer add-on settings

I have a client that is using Windows 10 with the latest updates. He has to use Internet Explorer for best compatibility with some Register of Deeds sites. When he tries to pull up a PDF it gives him a blocked message or an error. I went into add-ons and enable Adobe reader. It fixed the problem. But today he told me the problem came back. What latest Windows 10 updates would cause it to disable the Adobe add-on?

He can’t use Chrome because some of his software doesn’t work with it. Also, can’t use Firefox because he needs to use Java.