Just wanted to mention and show some positive news, that iSCSI Initiator X works fine on Mojave 10.14.6, after I helped the installation along in the "Security & Privacy" preference panel.
I have not yet gotten CHAP to work. Could be either a Synology NAS or an iSCSI Initiator reason. All combinations I tried gave the same dreaded e000001 error.
Axel