JWT token is always returning a ‘401 Unathorized’

Question

I'm building a an ASP.NET Core Web API that will consume some data entitie on Dynamics 365 F&O.

I've registered an APP on Azure and generated the neccessary credentials (client_id, client_secret, etc)

 

When i hit the endpoint directly from postman, this is what i get:

 

 

And when i use this access_token to make calls on the oData endpoint, i get a '200 OK' response:

 

Everything is fine up to this point.....

 

But ive wrapped the whole access token retrieval into a controller and when it hit the endpoint for this controller, i get access token...Cool!

 

 

 

But when i use the jwt token marked in black to make requests, i get a '401 unathorized' response, but despite checking from jwt.io, the token looks OK.

 

Someway somehow my token gets invalidated .

 

HAS ANYBODY FACED THIS ISSUE BEFORE???