I've posted elsewhere on this forum about this too but just to add here... Completed the campaign on xmas eve so bought the season pass, No syringe mission, no extra weapons and no Yak farm which I think should already be there too(?). I bought Kyrat edition from Amazon so already had Hurk and Blood Ruby which I also finished.
I've tried restoring licences and reinstalling game (more then once) but still nothing. Really disappointed and I guess time will tell if the future releases will become available to season pass holders.