Sam identifies as non-binary and uses “they, them and theirs” but while introducing them at iHeartRadio’s Jingle Ball, Shawn referred to the singer as “he”.
The Canadian singer-songwriter later apologised to the British star on Instagram, admitting “it slipped my mind”.
“I’m so sorry for referring to you as a ‘he’ for your Jingle Ball introduction,” Shawn wrote.
“It absolutely slipped my mind. Won’t happen again… Sending you so much love! Also you are absolutely one of the funniest people I’ve ever met!”
Oscar-winner Sam accepted the apology, saying: “We’re all learning together. Happy holidays, all my love xx.”
Sam asked fans to refer to them using the pronouns they/them in September last year.
They wrote at the time: “Today is a good day so here goes. I’ve decided I am changing my pronouns to THEY/THEM after a lifetime of being at war with my gender I’ve decided to embrace myself for who I am, inside and out.”