ConfirmRegister controller and register processor are hard-coded to use modFileRegister
Using registry.modFileRegister means activations fail in load balanced environments when the registration request happens on a different server to the activation request.
Would it i.e. help to make the properties in these lines configurable by a system setting? https://github.com/modxcms/Login/blob/master/core/components/login/controllers/web/ConfirmRegister.php#L130-L131
Sorry, but I don't have any experience in balanced environments.
Yes, I've forked the project, hopefully I can put together a pull request which allows a system setting login.registry_class to override the registry.modFileRegister with registry.modDbRegister.
I've had the modDbRegister working locally, but just bumped into some kind of concurrency issue when on a load-balanced environment (possibly a lingering database lock). Once that's fixed I should have something to PR here.
Maybe you could ask @opengeek wether he has some tip for this.