Hey @Sebastian_83, this is the expected behavior of JS queries in Retool. If you take a look at the debug tools in the app, you'll likely see that your JS query returns very quickly. I touch on this a bit in my post on asynchronous JS in the asynchronicity in action section.
Even in my async code, where I'm awaiting the return of the asynchronous API calls, the JS query returns in .005s. Which is too fast for the update on isFetching to give us any meaningful information.
The only way to make that JS query wait for all code to finish before it returns (and therefore give you the value for isFetching that you are looking for) is to create promise objects from the async calls and then resolve them before / when returning.
In my promises code, the JS query's isFetching property is true for the 4.6s in which that query runs.
Hope this helps!