ET's Kevin Frazier spoke with Thiessen at the premiere of The Secret Life of Pets 2 at the Regency Village Theatre in Los Angeles on Sunday, and the actress said that she "sadly" won't be able to be a part of the new series.
Thiessen -- who starred as Valerie Malone for six seasons, and joined the series around the time of Shannen Doherty's departure in 1994 -- told ET that her current contractual obligations on her Netflix series, Alexa & Katie, will be keeping her busy for the foreseeable future.
"I'm actually shooting season three of Alexa and Katie right now. So I am working at the moment and busy," Thiessen shared. "I'm literally in the middle of my season, and I go 'til September."
As for the upcoming series itself, Thiessen said, "I don't know too much about it but I know people are going to be excited."
"My shoot schedule sadly won't allow [me to be apart of it], but I wish them well," she added. "I'm sure it's going to be great."