This is not wpForo Core issue. It comes from your WP theme or from some plugin. Something affects wpForo JS and closes the form. I recommend deactivate all plugins, delete all cache, do Ctrl+F5 on forum front and test it again. If it starts to work, just activate plugins one by one and test after each activation to find the problem causer. If plugins don't do this conflict the problem causer is your current theme. You should contact to theme developers and ask them help you.

Thanks. It was in fact one of the plugins that caused it. Fixed that, but then to the next problem.

Post shows all formatting at the beginning of a paragraph and the last word of each sentence is replaced by "removed link" in grey. See attached image.

FYI, we're using the Knowledge Base theme and have assigned WP to wpForo so our understanding is that only the header and the footer are the theme and everything else in between is wpForo.

Are you sure forum editor looks like as it's here? I need make sure the editor is not crashed by theme or by other plugins. Also please navigate to Dashboard > Forums > Tools > Antispam admin page and set the "Min number of posts to be able post links" option "0".

Set the option as described. We tried another post and it seemed to work fine, so I believe we're good now. Thank you so much!