That's my standard setup across all the sites - that image approval is on in configuration, and that all the workflow options are enabled in the module.
I'm not sure what's going on - I seem to recall it happened on another website where I'm the moderator and received the email, but when I logged in, the module wasn't there and when I went to the Administrator to check, it was set up and apparently working.
If I see this again, I'll take a deeper dive into testing, but right now, Joomla's security version (3.9.1) and a few other extension upgrades have got me working my tail off!
Thanks,
Ernie