Hi @EmmaP!
I have encountered this. Even though the UI says that they are complete, they actually are not. While the query itself completed, the client is still fetching the data from the SQL Warehouse.
To check if this is your issue, from the monitoring page (shown in your screenshot) click one of the queries to open the details panel. Then check the "Result fetching by client" metric. While queries are in progress (or show as "Finished") -- If it's null or doesn't show a value, that means the client is still fetching the result.
This seems to really be a problem with Power BI - for some reason it leaves the connection open. I'm not sure if it actually completes fetching the data. Databricks kills these connections after one hour -- which is what I think you're seeing in your screenshot. After the one-hour timeout, the query should swap (I think) from "Finished" to "Failed" and show the error "Query has been timed out due to inactivity."
To combat this, I have a workflow that runs every hour to check if any queries are stuck fetching data -- and if so, kill the queries.