Got the time to look at it -- so the SNI required that the default server profile has server_name attribute set in order to register the SNI callback. I pushed a commit (see the link above) to register SNI callback for server default profile always. I will backport and it will be in 5.2.3 release.
For older versions, you can set `server_name=localhost` or another domain that you use with default certificate or if you don't have one, set it to something unlikely to be used.
I did the basic tests, but if still an issue, reopen.