Grafana Query in Variable failing

Hello,
I have a query type variable in grafana with an influxdb datasource (which is quite big) which has a query

SHOW TAG VALUES WITH KEY = hostname

This query works fine when I enter it directly into influx. The Variable however fails to initialise and it comes up with errors saying “Validation Failed to Fetch” and “Templating Variables could not be initialised: Failed to Fetch”. Ive tried this using

SHOW TAG VALUES FROM cpu WITH KEY = hostname

and this seems to work. It also works if I give the datasource an admin user.

Given that it works in these 2 cases I was thinking maybe the query times out, (since using FROM limits results to be taken only from 1 table, and using an admin user in influx generally reduces query times).
Is there any way to increase query times? Or if not is there anything else that I might do to fix this so i can use a non-admin user without the FROM?
Thanks

hello welcome to the forums, did you read the introduction sessions?

Im not sure, could you show me a link so i can see?