Cross-Origin Read Blocking (CORB) blocked cross-origin response

Ionic Framework
1

Hi

Hoping someone can help. When using JWT authentication with WordPress in a browser I am seeing a CORB error:

Cross-Origin Read Blocking (CORB) blocked cross-origin response https://mysite/wp-json/jwt-auth/v1/token with MIME type application/json

When I login via a browser or Android it works okay i.e. it authenticates.

However when I try login via a simulator or Apple device I get this error:

2019-07-17 16:34:05.530696+0100 MyApp[14743:3057062] Http failure response for https://mysite/wp-json/jwt-auth/v1/token: 0 Unknown Error

Any help would be greatly appreciated.

Thanks Mark