Grafana Dashboard Help - noob

I’m working on an aws rds grafana dashboard.
im using the promcat grafana dashboard as a base.

my issue is getting the templating dropdown to work

when i edit the dashboard
variables > query option
i have this:
label_values(aws_rds_cpuutilization_average, dimension_DBInstanceIdentifier)

anyways, if i go to this url:
<base-grafna-url>/aws-rds?orgId=1&from=now-7d&to=now&var-dbInstance=my-db-instance

it works (idk how i got the var in the url like that to work

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When i say it works, i mean it pulls the data for that DB
AND the dbinstance dropdown is populated with all the db instances that query should export

but the vanilla way to go to the chart does not work
<base-grafna-url>/d/xxx/aws-rds?orgId=1

this is where the dropdown shows None

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long way to say - anyone know what i might be doing wrong?
im just looking to get that dropdown to always populate my rds instances