Unfortunately, this is a client issue, and not an issue you can fix easily.
Most people would like to log on via one device.
The majority of the server I play on use iPhones. So, if the user needs to use the F2A App, it would timeout the MCPE client.
Besides this, I have checked over the code briefly, and Marked it as CHECKED on poggit.
I will test it fully tonight, to change it to Approved.