membership is not assigning subscriptions on registration

Hi Support,

I'm using the membership plugin, version 3.4.4.2 on a 3.7.x wordpress install and created different (free) subscription plans. On registering using the correct plan the subscription isn't assigned to the new user, instead the subscription level is left blank. The only thing i can change is the initially assigned subscription level in the general options which does assign that level.
Is this behavior normal?
in the support forum i could only find 1 relevant topic:
https://premium.wpmudev.org/forums/topic/membership-how-to-automatically-assign-a-subscription-level-upon-registration
But there is no answer there. Hope you can help
Regards