Hi Sargent,
If the user opt in the “Remember this browser” on their MFA screen, it won’t ask for MFA in the next 30 days so the silent authentication will succeeds.
If you don’t want to rely on the user’s behavior, you could also use this rule to customize the MFA trigger. Please remember if you use the rule to control when MFA is required, you need to turn off the “Always ON” MFA in the Tenant Dashboard > Multifactor Auth.