M2E Pro allows observing data changes triggered by various Magento Core Models. However, very frequently: Magento Products, Categories, Attributes, etc. are updated without a usage of Magento Core Standard Functionality (Magento Core Models), so M2E Pro may not detect these changes.
M2E Pro may not detect changes if:
If a data in your Magento system gets updated by any of above-described methods, there is a requirement to notify M2E Pro explicitly. There are 2 options to do that:
These models can be found in your Magento File system in the following path: app/code/community/Ess/M2ePro/Model/PublicServices.