"Narcos" star Stephanie Sigman -- the hot Colombian reporter who hooked up with Pablo Escobar -- was nowhere to be seen at the season 2 premiere ... because she was snubbed.
Production sources tell TMZ ... the show didn't mean to diss Steph ... it was more a case of out of sight, out of mind. Although her role in season 1 was pivotal, her involvement in season 2 is spotty.
For her part, we're told Stephanie was real upset when she didn't get an invite, but she stood on principle and never contacted producers ... thinking it was intentional rather than an oversight.
So Wednesday's party was awesome, but not as hot as it could have been.