Michael Jackson Tribute Concert -- Jennifer Hudson Left Us in the Lurch

Jennifer Hudson's no-show at the Michael Jackson tribute concert yesterday caught the show's producers completely off-guard ... especially since she was already paid to do the gig ... this according to sources close to the show.

JHud tweeted Saturday afternoon she wouldn't be doing the show -- citing "major production issues."

According to our sources, Hudson is claiming she felt the show's producers didn’t give her enough time with the music she was supposed to be singing. According to our sources, Jennifer received her music the same time as all the performers.

Our sources say JHud signed her contract and was paid in full.