Can not create 10 Containers via Terraform

HiHo, i try to deploy 10 containers with CICD and terraform via the LXD API. but in the first pipeline run some containers not getting created. I can see in the console of the gitlab runner all of them getting triggert to be crated, but these ones are not getting deployed, are also not visible in /var/log/lxd/lxd.log. Are there limitations on the LXD API?
When I run the partially failed gitlab stage again, the missing containers getting deployed successful also.
My container host is based on Ubuntu 18.04.