Yes they had this until the end of 2019 issued on Dutch ticket stock, and then for a couple of months in 2020 issued as an e-ticket. The current situation is supposed to be a temporary measure as NS weren't selling tickets through third parties.
Rover (Dutch passengers' organisation) asked NS last year why the combi tickets (to any Dutch station) had been discontinued and if and when they will come back. NS replied:
"The cooperation with Stena Line for the e-tickets was a pilot. The results of the pilot were not positive for the various transport companies, which made it undesirable to continue in this form. We are currently working hard on new technical possibilities and payment methods in various areas. This offers opportunities for the future.
However, this is for the long term. It is not yet known exactly when this will be ready. Because these new developments are imminent, we have chosen not to make any major adjustments to continue the pilot. Therefore, we do not offer a combi-ticket at the moment. We are waiting for new technical possibilities and payment methods and will
then consider, together with all parties involved, whether the pilot can be continued in the future."
When asked, NS could not give any indication about when approximately they think combi tickets would be available again.
This is all very unsatisfactory but it seems NS just don't want to do anything about this at the moment.
Before the Dutch part of the combi ticket was sold as an e-ticket, it was a physical ticket, which was only available for passengers in the Netherlands (when sold by Stena in any case - not sure how it worked for the Dutch Flyer that Greater Anglia sold). This was also unsatisfactory but at least there was something available.