Enteric-Coated Tablets Problem

I regularly take an enteric coated supplement (Rejuvenzyme) - these are designed not to release until they travel into the small intestine.

Regularly (but not always) I experience a situation where these capsules do not seem to move through the stomach to the SI - I know this because I regurgitate them in whole form anywhere from 2h to 8h later (I re-swallow and I guess they eventually pass through)

Has anybody ever experienced something like this or does anybody have any ideas why this might happen?