What’s not true?
The modern versions listed here omit the word “Lord”, apart from the Amplified Bible that puts it in square brackets.
https://biblehub.com/parallel/1_corinthians/15-47.htm
Which modern English version do you say includes the word “Lord”?
The earliest MSS, including Vaticanus and Sinaiticus omit “Lord”, and modern critical editions of the Greek New Testament omit the word too: NA28, UBS5, Tyndale. That’s the reason modern versions don’t include the word in the text.
Nevertheless, Jehovah’s Witnesses believe Jesus is Lord and would have no trouble saying so then or now, or quoting the King James in this verse, as they often did in that period. They believe Jesus is God’s first creation and second in the universe only to God himself. This is what they taught in The Harp of God and it is what they teach now.