@fenwick67 Another user, @lewismcmahon, has forked that plugin and is supporting it now. It is nodebb-plugin-s3-uploads-updated and can be found in the Download Plugins section of the ACP. No need to manually install the one I referenced originally.
EDIT: It looks like you edited your post as I was composing this response.
Possibly sounds like a browser script crashing. What is the full list of plugins you have installed?
It appears that rebuilding the forum + refreshing the page enabled access to the pages.
However, I still cant make any Search Plugin work on my forum properly, be it DB search, Elastic or Solr. I'm using a non-roman alphabet ☹