Custom Domain Not Accessible via Internal Network - Any Ideas?

Hey friends! We have a custom domain, learning.ourcompany.com. We have configured the SSL cert and DNS properly, and we can access the site no problem UNLESS we are on our internal network. We use windows DNS manager for our internal network and we have tried adding a CNAME Alias pointing to ourcompany.docebosaas.com, but that isn’t working. We’ve whitelisted the domains that the Docebo support team told us to whitelist. We can get to ourcompany.docebosaas.com via our internal network, but not to our custom domain. Docebo support team is saying they can’t help us any further because this is an internal network config. 

So my question to you fine folks is: has anyone come across this kind of issue before with an internal DNS manager, and what was the config that fixed it? Many thanks for any and all guidance!