Refresh access token with OpenAPI

When I launch my application, first I send a ProtoOAApplicationAuthReq, and then a ProtoOAAccountAuthReq, when the access token is out of date I get an error message with "CH_ACCESS_TOKEN_INVALID"

Then I try to update it sending a ProtoOARefreshTokenReq message using my current (out of date) token but I get another "CH_ACCESS_TOKEN_INVALID" as response, I have also tried with another (random) token with the same result.

How can I refresh the access token with OpenAPI?

Thanks.