I’ve the same problem so i called the Degiro support and they told me that all ETF based on US Stock Exchange are not tradable any longer.
With my big surprise I told them that this is new to me and no information has been provided. Moreover, there’s a file on their website which is showing a long list of free-commission ETFs including all Vanguards.
Conclusions, I’ll be selling all my positions and close Degiro account and move it to somewhere else.
P.