RETENUE SUPPLEMENTAIRE USA - dividendes

[Dr.PI]

Do you use a foreign broker and have selected R-US withholding tax, by chance?

DA-1 for "Vanguard VTI ETF" rejected with "Kein R-US, da ausländische Zahlstelle"?

I’ve successfully filed a DA-1 for the Vanguard VTI ETF (among other ETFs) for several years without problem but this year I got the DA-1 rejected with the (very short) motivation “Kein R-US, da ausländische Zahlstelle”. Could someone elaborate on what that might mean? I guess “R-US” is just short for “Rückerstattung-US”. If it matters the ETF is held in my Interactive Brokers account.