Update session creation is not supported for library item

I’m trying to build a template using packer and pushing the template to a content library, but for some reason right as it’s about to complete it fails with:

Build ‘vsphere-iso.linux-rhel-base’ errored after 13 minutes 46 seconds: deploy error:
Update session creation is not supported for library item
‘nats-rhel9-template’ (ID: a898643f-1ee9-4014-851d-adf58fe6dafa) because it contains a virtual machine template.

Any idea what could cause this?