ALL listing lost buy box, no featured offer

Hello,

My seller account lost the buy box for all the listing in the Germany marketplace as no reason. Before this, the listings and shops were all making orders normally. Please upgrade the investigation.

I cannot see any helpful ideas from Amazon DE support on seller forum.

What can I do now ?

I have see some poster on UK seller forum, they mentioned that there is a buy box team? but how to contact them, and if they can solve the same issue on DE marketplace ?