I was following a tutorial that led me to write Axios instances like this:

const baseURL = GuardServices.returnApiUrl();

const axiosInstance = axios.create({
    baseURL: baseURL,
    timeout: 15000,
    headers: GuardServices.getHeaders()
});

axiosInstance.interceptors.response.use(
    (response) => {
        return response;
    },
    async function (error) {
        const originalRequest = error.config;

        if (typeof error.response === 'undefined') {
            alert("An error seems to have occurred, please refresh.\nIf problem persists please contact system admin.");
            return Promise.reject(error);
        }

        if (
            error.response.status === 401 &&
            originalRequest.url === baseURL + 'token/refresh/'
        ) {
            AuthServices.logoutUser()
            return Promise.reject(error);
        }

        if (
           error.response.data.code === 'token_not_valid' &&
            error.response.status === 401 &&
            error.response.statusText === 'Unauthorized'
        ) {
            const refreshToken = localStorage.getItem('o$FX1HM77H3gq0AI');

            if (refreshToken !== null || refreshToken !== "null") {
                const tokenParts = JSON.parse(atob(refreshToken.split('.')[1]));

                // exp date in token is expressed in seconds, while now() returns milliseconds:
                const now = Math.ceil(Date.now() / 1000);
                // console.log(tokenParts.exp);

                if (tokenParts.exp > now) {
                    return axiosInstance
                        .post('/token/refresh/', { refresh: refreshToken })
                        .then((response) => {
                            GuardServices.updateHeaders(response.data)

                            axiosInstance.defaults.headers['Authorization'] = GuardServices.getHeaders()
                            originalRequest.headers['Authorization'] = GuardServices.getHeaders()

                            return axiosInstance(originalRequest);
                        })
                        .catch((err) => {
                            console.log(err);
                        });
                } else {
                    AuthServices.logoutUser()
                }
            } else {
                AuthServices.logoutUser()
            }
        }

        // specific error handling done elsewhere
        return Promise.reject(error);
    }
);

However, it came with some unanticipated occurrences. My callbacks do not execute on mobile devices, and some browsers. I haven't come across this issue before and have had little luck finding anything about it online.