JWT mutli refresh-token issue

Hello
I am facing an issue with refresh-token support mechanism.
As far as I understand, Nebular handle refresh token by invoke of **isAuthenticatedOrRefresh** method.
While sending a bulk of http requests to the server, Nebular handler recognizes that a refresh-token is needed and sends a lot of requests(1 per each request) for refresh-token instead of waiting for one refresh-token to return.
In that situation, the first refresh-token request returns ok and the corresponding http request gets the required data with no problem, BUT, the other requests, fail.
Attached you can find the result as we get them on Network capture.
Please advise how should we handle refresh-token while working with Nebular.
Is it a bug or wrong way of implementation?
Thanks in advance,