Thanks a lot for your feedback!
I redid the tax info a couple of months ago. That was weird, because that was the first thing I checked when I realised the payout was kind of stucked. At that time the tax info was right. A few weeks later, it wasn't so I did it again.
Today I've made some changes in my settings because I noticed a (new?) error.
Apparently, there have been some issues with Paypal, and the "version" I was using so far was now considered obsolete. I had to reconnect to the "new" paypal. (-> account settings -> publisher -> payment processors).