Hi Geert,
Please check the following -
1. Perform the product catalog replication - Initial Replication once again.
> Before the replication, please ensure that the product catalog and the related sub nodes are active
> Also the product catalog variant is active and end date have not reached against the variant (this is valid only if you are maintaining the start date and end date against catalog variant)
2. Hope you have also entered the correct product catalog, catalog variant Id in the respective shopadmin settings. Please check this once again
3. If above does not work, then refresh your custom webshop from the NWDI.
Hope this will be helpful.
Thanks and Regards
DJ