Looks to be working for me
Try clearing your browser cache.
A few other questions:
1. Does this happen on all of your devices?
2. Which browser does this occur the most on?
3. Have you tried different browsers?
I'll also need the thread and post you last tried it on and if you can, try multi-quoting this post here.
The WYSIWYG editor is all JavaScript, so ideally it would come down to an issue on the client-side (your device/browser) or the forum asset side (where it loads the JavaScript that inserts the quite into the reply box.