We have encountered a few cases where the login screen restarts, or closes in the case of RDP, before showing the Mi-Token OTP field.
This has been caused by an error recorded in the computer's even viewer under Windows Logs/Application, event ID 1000 and related to LogonUI.exe as shown below.
Sometimes this happens after a software update, or we have also faced this with certain hardware from Dell. Our Credential Provider is shipped with an older version of the LIBEAY32.dll library. Usually, overwriting it manually with a newer version solves the problem.
This solution from our FAQ contains the latest validated component for download.
This ticket was the source of the reported problem:
[#45776] Yubikey MiToken and new Dell desktops : Mi-Token Inc