I checked again, they appear now again on most OTAs.
FN shows them at the non-discounted price.
Justfly is unable to price the full trip in business, the first intra-European shorthaul is now in economy. I quickly checked on KLM and there are plenty of business seats available on that flight.
The availability on MF website remains the same.
This whole booking process on MF is a bit messy...
What OTA did you use to book your itinerary?