'Vanderpump Rules' Stars Confident Rachel Leviss Isn't Returning For Season 11

Rachel Leviss' possible return to "Vanderpump Rules" remains shrouded in mystery ... but as filming keeps rolling along, her costars are becoming convinced she won't join the fold.

Sources connected to the hit reality show tell TMZ ... 'VPR' cast members are now feeling more than confident Rachel will NOT return for Season 11.

There's reasoning behind the consensus ... the cast has been filming since late June and Rachel hasn't shot a single scene, either solo or with any other 'VPR' stars.

Bottom line ... it's going to be hard to integrate Rachel into the storylines.

What's more, we're told none of the cast, aside from Tom Sandoval, has been in touch with Rachel since they saw her at the emotional reunion show in late March, which was shot just before Rachel checked into a mental health facility, which she recently left after a lengthy stay.

However, never say never ... we're told 'VPR' stars wouldn't be shocked if Rachel shows up to film at the 11th hour to tell her side of the story about the Scandoval.

Still, our sources say other cast members strongly believe Rachel's therapists convinced her to steer clear of the show and the accompanying drama that led her to seek professional help in the first place.