This is the answer to the issue actually. You have to add all variations of a websites address.I have the same problem , did you found a fix?
I found a way to regain chat button not greyed out , I edited in 3cx admin chat settings and I changed my website url from https://fqdn to https://www.fqdn and then, tada....button became active.
Hi,changed my website url from https://fqdn to https://www.fqdn
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.