MySQL cannot connect with Read-only user

Good day, I am using Grafana cloud for reporting visibility to our MySQL database. I built the initial dashboard and panels with a user account that has select,insert and update privileges on the database. I have tried to change the datasource config to use an account that only has select privileges, same host same database. The test of the datasource fails on the restricted user account. I can plug in the same credentials for the restricted user account in HeidiSQL or MySQL Workbench and it can connect and query data. Any suggestions about what Grafana may be trying to do on connect to validate the connection? I have asked DBA to look at the logs and see if they see the rejection reason.

Thanks.

Can you verify that you user has access from anywhere?

SELECT user, host 
FROM mysql.user 
WHERE USER = "GrafanaReadOnly";

Good question. Yes, the read-only user is not restricted to a host.

Now have it working after DBA reviewed grants. Trying to get details in case it helps anyone else with similar issue.