Unsubscription 'Goodbye-Message' not working properly

Hello,
previously I encountered that the 'goodbye-message' won't show up at the end of the unsubscription process of one of my sites.
The process itself just works fine, the user gets unsubscribed and receives the 'goodbye-email' relativly quickly but the last message on the website is missing, instead the user will be forwarded to the start page.

I know the problem should be fixed in the newest version of the plugin, but somehow it isn't for me..

I would appreciate suggestions on how to fix my problem without losing all of my settings (lists, imported users etc.)

Sincerely,
Cedric