Cannot enable notifications via Chrome (mobile) browser

I am working on a site, which should notify users of a new message coming in. This works well in Chrome on Desktop, but in Chrome on Android - no matter what I do, despite having all the notifications enabled for this domain, I still cannot get notifications to be received. Any idea where else I can check for this? Same results when a friend tested on his device as well. Could it matter that this is on a subdomain, where the parent domain does not have permissions allowed (but also not blocked)?