Thank you for bringing this to our attention and I'm sorry to hear that outriders aren't spawning.
I can see that the issue with outriders not spawning following TU 1.5.1 has been already reported to the development team and it's currently being looked into. In order to speed up the investigation, can I kindly ask you to provide us with a short video of this occurring? Additionally, can you please make sure that your save game is already uploaded to the cloud?
Many thanks and if you have any additional questions, please let us know. Apologies for any inconvenience caused by this.