Shield... no route found

Hi everyone,
I am not sure, either my problem is very special or I am just dumb. At least I tried something with Shield, it worked all fine, had some testing and just after putting it online it broke...
So I managed to adjust Shield to accept UUID as field for login. It sends an email to this uuid (done by the Email activator. It's some magic, I'll leave this as blackbox here) and waits for a confirmation code, so far so good. The url for this is auth/a/show as expected. First thing I notice, once one tries to reload this, it gives a 404 error.
Next thing, once one enters the code it should redirect to auth/a/verify with the post request and the confirmation code. But it always gets a 404 error as well!
"php spark routes" shows everything fine and in order

PHP Code:

| GET    | /                      | »                  | \App\Controllers\Home::index                                      |                | toolbar      |
| GET    | register                | »                  | \CodeIgniter\Shield\Controllers\RegisterController::registerView  |                | toolbar      |
| GET    | login                  | »                  | \CodeIgniter\Shield\Controllers\LoginController::loginView        |                | toolbar      |
| GET    | login/magic-link        | magic-link        | \CodeIgniter\Shield\Controllers\MagicLinkController::loginView    |                | toolbar      |
| GET    | login/verify-magic-link | verify-magic-link  | \CodeIgniter\Shield\Controllers\MagicLinkController::verify        |                | toolbar      |
| GET    | logout                  | »                  | \CodeIgniter\Shield\Controllers\LoginController::logoutAction      |                | toolbar      |
| GET    | auth/a/show            | auth-action-show  | \CodeIgniter\Shield\Controllers\ActionController::show            |                | toolbar      |
| GET    | about-us                | »                  | \App\Controllers\Home::page/about-us                              |                | toolbar      |
| GET    | links                  | »                  | \App\Controllers\Home::page/links                                  |                | toolbar      |
| POST  | register                | »                  | \CodeIgniter\Shield\Controllers\RegisterController::registerAction |                | toolbar      |
| POST  | login                  | »                  | \CodeIgniter\Shield\Controllers\LoginController::loginAction      |                | toolbar      |
| POST  | login/magic-link        | »                  | \CodeIgniter\Shield\Controllers\MagicLinkController::loginAction  |                | toolbar      |
| POST  | auth/a/handle          | auth-action-handle | \CodeIgniter\Shield\Controllers\ActionController::handle          |                | toolbar      |
| POST  | auth/a/verify          | auth-action-verify | \CodeIgniter\Shield\Controllers\ActionController::verify          |                | toolbar  


If anyone has any idea or how to help, I'll be very happy. If a demo url can help, I can provide one.