Forwarding to welcome page of tiers not working

Hi!
I am not sure if that is a ghost related issue or a problem with my used theme.

I created several tiers and added welcome pages for them. Unfortunately a user will not be forwarded to the page after he subscribed to one tier. Instead he will be forwarded to the homepage. Is there something I missed?

I am using the newest version 5.9.1 of Ghost.