getTokenSilently returning token after delay in InCognito mode

What We are seeing is getTokenSilently works fine in normal window. But in InCognito mode, the getTokenSilently not returning the token immediately after login. The token is available later on consecutive calls. We have made the cacheLocation="localstorage" still we are seeing this issue.

To analyze it further we placed a sleep/wait before the getTokenSilently and now We are getting token as expacted. Please assist on the issue