Assigning roles to groups using deployment manager

I tried to assign roles to groups using deployment manager.
First error, I received is
ERROR: (gcloud.deployment-manager.deployments.create) Wait for Operation [operation-1644329044917-5d782309dbb3a-fe42e51e-e4033d4b] exceeded timeout [1200].
but the deployment is running even though the error is thrown. It took more than an hour but it throwed the second error
{"ResourceType":"gcp-types/cloudresourcemanager-v1:virtual.projects.iamMemberBinding","ResourceErrorCode":"409","ResourceErrorMessage":{"code":409,"message":"There were concurrent policy changes. Please retry the whole read-modify-write with exponential backoff.","status":"ABORTED","statusMessage":"Conflict","requestPath":"https://cloudresourcemanager.googleapis.com/v1/projects/nowtv-adload-discovery:setIamPolicy","httpMethod":"POST"}}

If I run an update command, it will complete without any error. This is the case with the deletion as well.

Please suggest.