Cummings, who executive produced the Roseanne revival, questioned her past interactions with Barr during Wednesday's episode of Watch What Happens Live.
Cummings was asked to share the biggest lesson she learned while working on the Roseanne revival, which aired on ABC in 2018.
"The lesson I learned from the Roseanne reboot is read people's tweets before you sign up to work with them," she said.
Roseanne was canceled in May 2018 after Barr's tweet about former White House advisor Valerie Jarrett and was rebooted without Barr as The Conners. Cummings said she hasn't spoken to Barr since production on Roseanne.
"I don't think I've ever spoken with her. I mean, during, I never knew who I was talking to now that this has all happened. I don't know if I've ever actually spoken to her," she said. "But yeah, not since during production."
Cummings, an avid Sex and the City fan, also discussed how director, writer and executive producer Michael Patrick King gave her Carrie Bradshaw's mirror from set. Sarah Jessica Parker played Carrie in the HBO series.
"He did give me the mirror that was on Carrie's boudoir. It is now in my closet, the actual one that Sarah Jessica used as Carrie," she said. "It is my most cherished possession."
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Cummings is known for creating the CBS series 2 Broke Girls. She will write, produce and star in the new Amazon comedy pilot Good People, which co-stars Lisa Kudrow and Greg Kinnear.
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