Visual Option Missing

I installed the plug in 3 months ago and absolutely love it. The problem is recently when I go to edit the content, only the “text” option is available showing the coding. The “visual” option is no longer there. This is going to be a problem for the other manager to use as she is not at all familiar with coding or what the “text” means. Can you help me get the “visual” option back please?
Thanks

https://ww.wp.xz.cn/plugins/rich-text-excerpts/