Hello @Gimenez, Miguel , Thanks for using Microsoft Q&A Platform.
Query fields are currently only active for resources in the
East US
region.
As mentioned, this is available in East US region. I just reproduced the same using East US I was able to that. So, this error is due to the West Europe region as it is not supported. https://learn.microsoft.com/en-us/azure/applied-ai-services/form-recognizer/whats-new?view=form-recog-3.0.0&tabs=csharp#march-2023
Please try this and let us know if you face any issues.
I hope this helps.
Regards,
Vasavi
-Please kindly accept the answer and vote 'yes' if you feel helpful to support the community, thanks.