In the recent 22.214.171.124 release of Magento, they introduced a bug which affected the XML-RPC service. Remarkety uses this service to retrieve recent information about the store's shoppers, products and orders.
If you currently have this exact version installed, Remarkety will not be able to synchronize with your store.
Magento recently released a version which addresses this problem and several more (release notes here). We have verified that stores upgrading to the 126.96.36.199 version can once again sync successfully.
We therefore advise you, if you've installed the 188.8.131.52 version, to upgrade as soon as possible to the 184.108.40.206, and check that Remarkety is synching with your store.