Big Table Java Connectivity issue

Question

Am trying to connect to big table from a java spring-boot application. Am using bigtable-hbase-2.x.

Am using BigtableConfiguration.connect(projectId, instanceId)

During the application start up am seeing this warning in the logs

c.g.c.b.d.v2.stub.BigtableChannelPrimer  : Failed to prime channel: com.google.api.gax.rpc.PermissionDeniedException: io.grpc.StatusRuntimeException: PERMISSION_DENIED: Access denied. Missing IAM permission: bigtable.instances.ping.

But after 10 such warnings the application starts up automatically.

When am trying to save data via the application

• Any write fails. Uses standard way of table.put
• It fails with PermissionDenied exception

Things I did to debug this

• Validated the IAM user using in my local for connection. The user has BigTable.Admin role.
• The BigTable.Admin has standard access to all operations as per the link

Need helpers or leads on below

• What could be wrong with the permission that is causing this?
• Why is the Access denied. Missing IAM permission: bigtable.instances.ping. is thrown in spite of being a Admin ?