Hi Nicolas,
What I did before the upgrade, was the following;
1. made Akeeba backup of production site (Joomla 3.4.1 and Hikashop 2.4.0)
2. Restored to testserver
3. upgraded testsite to joomla 3.4.2 and hikashop 2.5.0
4. Purged Joomla cache
After the upgrade, both badges (nieuw and aanbieding) were present on all products on the testserver.
I was able to resolve the problem today by:
1. Remove the existing category from each badge.
2. Save
3. Add the category that was removed in step 1 to each badge
4. Save
Regards, Benny.