It is just a matter of time.
Amazon takes time to update their systems with the newly-communicated stock availability. Same sometimes with pictures. This means that it normally just takes time (several minutes, sometimes a good half-an-hour) and your availability will magically appear in Amazon.
This is not due to Nembol. It is really just Amazon taking some time to get up to date. It is understandable as they manage a complicated system.
Check your products in Amazon Sellercentral after some minutes and everything will soon be alright.
These are examples of products that had a positive stock quantity in Nembol when they were published to Amazon, but quantity zero in Amazon at the outset. After a little while, they were all ok: