Load CSP policy first?

I have a website which uses a (rather old) plugin called “Require logins”.
If I have it enabled it shows a login box prior to allowing users access to content.

At the same time, the problem is that this also seems to prevent verifying CSP policys.

I’m not sure whether you can give any hints in this, since you naturally would not know other plugins than your own, but if you have any ideas on how to get around this I’d be grateful. As a workaround I can of course temporarily disable the plugin, scan and then re-enable it, but I would if possible like to avoid that.