SSL_ERROR_RX_RECORD_TOO_LONG on Kali is caused by using Java 11 (installed and set to default in Kali). Even though Burp does send requests and receive the responses, for some odd reason, the browser receives this error from Burp. And to make things more confusing, there’s no message in the Alerts tab that something is wrong.
The fix is simple:
update-alternatives --config java and set to Java 8.