The exes shot the HGTV show on Thursday, a source tells PEOPLE.
Their joint filming for the HGTV show comes a week after El Moussa, 39, reportedly berated Haack, 38, because he didn't like the way she signaled to him that she and the crew were ready to film the next segment, TMZ previously reported.
Haack shared photos from set Thursday, including a shot of her "morning glam," in which she rocked neutral makeup and soft curls with braids swept back into a half-up, half-down style.
Another picture showed tiles laid out for an upcoming "Spanish style flip."
Christina Haack/Instagram Christina Haack
El Moussa's fiancée, Selling Sunset star Heather Rae Young, posted a selfie with her husband-to-be on Thursday, revealing that she was joining him on the Flip or Flop set.
"Babies filming at one of his flips today," Young, 33, captioned the picture, adding, "Go to work with hubby day."
Christina Haack/Instagram Flip or Flop set
During El Moussa's reported blowup last week, he allegedly raised his voice and spoke down to Haack, saying that he enjoys watching her fail. He also compared her to Young.
A source told PEOPLE that El Moussa is "super remorseful" about his verbal tirade against Haack.
"They did get into a disagreement. Tarek lashed out and he's super remorseful," the insider said. "They're exes who share a history and children and a workplace, but outside of coparenting, they're not friends."
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Heather Rae Young/Instagram Tarek El Moussa and Heather Rae Young
El Moussa and Haack were married from 2009 to 2018, and both found fame with the launch of their series Flip or Flop on HGTV in 2013. They both now have solo series on the network, Haack's Christina on the Coast and El Moussa's Flipping 101.
Haack and El Moussa — who share daughter Taylor, 10, and son Brayden, 5 — have filmed nine seasons of Flip or Flop together and are currently working on season 10. The show follows the divorced duo as they navigate life as co-parents and real estate experts flipping run-down homes in California for a profit.
A day after news broke out about the fight, Haack shared several videos from a day on the set of Flip or Flop, making it known that El Moussa was not there as staffers repeatedly called her "the boss" for each executive decision.
"Nice day on the Flip or Flop set," she captioned a video on her Instagram Story showing crew members walking around — with El Moussa noticeably absent.
RELATED VIDEO: Tarek El Moussa Is 'Super Remorseful' He 'Lashed Out' at Ex Christina Haack, Says Source
Last week's confrontation isn't the first time Haack and El Moussa, who are both executive producers on Flip or Flop, have had a falling out on set. A source told TMZ that there have been times where they'll stop filming together and simply shoot their scenes separately.
Haack recently made news for dating Austin-based realtor Joshua Hall, whom she began a relationship with shortly after her divorce from second husband Ant Anstead. She and Anstead were married for less than two years, and share son Hudson London, 22 months.
El Moussa proposed to Young in July 2020, and the pair are renovating a house in Newport Beach together.