Cannot accept Family Premium via email

[Wugo]

Hello everyone,

my sister upgraded her account to Spotify Premium for Family and invited me via email.

The Problem is that I am still unable to join. There is always an error message, telling me that I cannot join and that the owner has to reinvite me.

The owner reinvited me and also deleted and added me again, but it did not work.

I hope that someone can help me.