I had the option to blur my background on Video calls. That option has disappeared. When I go into settings, background & filters, there is no "filters" tab. How can I correct this?

Are you referring to RingCentral Meetings or RingCentral Video?

RingCentral Meetings.

I Only have the Virtual Backgrounds. I do not have the "Filters" option

I don't think so. I was the host of the meetings where I used it. Also, I believe I found that option as an example on the internet when I did a search for blurred background on RingCentral. But I am an old married guy with kids, so it is possible that I am completely wrong - just ask my wife, she'll tell you. I chose to think of it as part of my charm. . . In all seriousness, I know that I have used three versions of RingCentral meetings. One from the Web, from the new RingCentral App, and from the old RingCentral App. It would have been either the old app or the web version.

RC website says blur is available but it's not actually available in my RC app

It is RingCentral Meetings

RingCentral Meetings doesn't have the blurred background available. You can use RingCentral Video instead. There are lots of great features available on it. Check out this link, https://support.ringcentral.com/article/RingCentral-Video-Overview.html