A few thoughts:
I’ve found APIs put info in the darnedest places, so I always display error, status, and response when debugging:
It looks like you need 2 header properties:
curl -v -X POST -H “Ocp-Apim-Subscription-Key: lOEflwP0ouh9tv6zmKr” -H “Content-Type: application/json”
Don’t be like me and try to put them in a list. It should be one object with 2 properties.
I think the url should be in the body, not the header ( but I might be wrong).
When using the body, you cannot use Thunkable object blocks directly, you need to GENERATE JSON FROM OBJECT (because Thunkable)
I’ve struggled to get the parmeter block to work consistently. Here is an example of it working
Unfortunately, sometimes I resort to JOINing a long URL block 
. Honestly, I usually start here, and once I get it to work, I move them to blocks, because Thunkable.
Happy Thunking!