Not sure if this will work but try adding a new bullet in and have it in the direction yo want it to go in the game, then spawn it from that. The spawner might be reading the bullet how you imported it and not adding the rotation. You can also try the edit screen for the bullet and rotate it there. Hope this helps
I know this is an old post but if anyone finds the same problem the above post fixed it for me! Because my enemy was facing right on the main object and i placed him and used -1 scale to face him left in the scene he spawned upside down! I went on to my object animation and added the -1 scale there so in the scene it is now 1 not -1 so when you now do the spawner it will be corrected