Print to the console received 'Invitation' and check does it contain this attribute (search line 'a=ice-ufrag:'). When line missed - check server settings (is enabled ICE).

Here https://community.asterisk.org/t/failed-to-set-remote-answer-sdp-called-with-sdp-without-ice-ufrag-and-ice-pwd/77997/11 explanation of the similar issue.