Scan not running

Select to run scan, and it says it is Requesting New Scan, then after about 5 seconds – times out.
Have read the default page on the wordfence site about cache, htaccess, don’t have any blocking in place on my site, yet it won’t run.
Where else to check, what could be causing it to not run?

https://ww.wp.xz.cn/plugins/wordfence/