The text based protocol can't transfer LSA_TRUST_TYPE_MIT (with sid = NULL) domain in the trust list, which causes the parent to stop processing the trust list.
The problem was noticed with 3.6 and I got notified that it's already fixed in newer versions. Commits aa3f10c61e90e55f2763dd3cb70e8920edc80ab4 and 3c0b88275629749fba23f0a04cec1aa0a6362927.