Hi bertjan ,
Sorry, but I can't know what happens on your site with so little information.
What type of products do you use?
Have you installed any cache plugin? And your service provider? If so, please try deactivating the cache and tell us if that fixes the problem..
The Wholesale Suite Plugin shouldn't affect Stock Central, but I can ensure that at 100%. You can chech it by temporarily disable the plugin.
Best Regards,
José Andrés