Error: Specified seed repository does not contain backup of the required VM

Did you check the pre-reqs for replica seeding?

https://helpcenter.veeam.com/docs/backup/vsphere/replica_seeding.html?ver=120

Also, this is not a Support forum.  If you need to get technical support, then open a support ticket and post on the Forums for further assistance - https://forums.veeam.com 

A couple requirements @ronomatic for your target side Repo is it cannot be a SOBR the backups reside in. Also, you must perform a rescan of the Repo the copy of the VM backups are in. And that’s pretty much it.

If it’s still not working, the only other option would be to open a support case as Chris suggests. Mapping has a higher priority than Seeding, but I see you don’t have Mapping enabled, so the job using Mapping over Seeding isn’t the issue.

Here’s the info from the Guide on how to create the Seed:

https://helpcenter.veeam.com/docs/backup/vsphere/replica_create_seed.html?ver=120

I’ve only seen this when I setup backups and replica’s at the same time, but the backup hasn’t yet run to place data into the repository to use as seed data. In that case, I wait until the initial backup has run, or I start the replication without using seed data from the back repo.  If these scenarios don’t fit your use case, I’d proceed with support to determine the source of the issue as I’m not sure what would caused seed data to not be seen in the repo if it is there.