The issue may be caused by not using the latest version of a particular browser. My Firefox has this problem (its not the latest version which I refuse to download). I now tried accessing The Forum on Edge and the problem seems to have cleared up. So I guess I'll do The Forum on Edge from now on. Everything else on Firefox.
None of the little "helper " buttons at the top are working, line the insert link button or font buttons, And I also have been having a hard time attaching files or adding photos. I thought it was me. Maybe be part if the most recent installed updates from microsoft.