Right now, this does require Support to enable, I'm afraid. In many cases, the need to have these enabled is documented in the relevant KB article https://meraki.cisco.com/meraki-support/open-a-support-case/ ...though not in this case, I notice; I have just requested internally that this be added.
When I get chance I will do some digging as to why this option isn't available in the UI too. On the face of it, I can't see wht that's not been done already, TBH - but engineering tend to have visibility of all the potetntial complications. What I'd recommend is speaking with your Meraki account team to make a formal request on your behalf; the Community isn't really a forum for that.
Note you can raise a case via the Dashboard, rather than wait on the phone (though I'm surprised you've been waiting 30 mins - it's not usually that busy).
If you can't access Dashboard, cases can also be raised online: https://meraki.cisco.com/meraki-support/open-a-support-case/