CSEP Store review for Mailchimp Email SMS Marketing

If you have too many different customer tags in Shopify, this app stops syncing any customer tags. We've spent 3 weeks full-time trying to fix this with no luck. Then it synced tens of thousands of old contacts from Shopify to Mailchimp with no way to filter them out, doubling our Mailchimp costs due to extra subscribers. We will have to pay a developer to build a custom Shopify-Mailchimp syncing app to compensate for this app's deficiencies. Edit: I've tried all combinations of options, including trying to only sync specific tags. That didn't work either.