Spark unable to register new users

I have a fresh install of Spark and have ran npm install, gulp and artisan migrate. When I access my site locally all seems to look ok, but if I click on register and try to register a new user I briefly see the page render with seemingly validation errors on it for approx 0.2 of a second then I get returned to the empty register page. I check the database (all tables exist as per migration and database user has right permissions) but no user has been created.

Has anyone else experienced this, or can indicate how I can troubleshoot the issue further please?