Typically, when a user cannot get logged in, that is going to be one of two things.
#1 Invalid Login ID \ Email
#2 Invalid Password
How to know if the login\email is the problem or if it is a password problem?
If the problem is an invalid login ID or email, the user will NEVER see a message about login attempts. For example, look at the images below, this is a valid Login but a WRONG password. The user is being told that they have failed 3 attempts, and it will eventually LOCK the account.
If the user never gets the warning about too many failed attempts, that is likely a problem with the user's Login ID or Email. TimeTrakGO allows users to enter their email or Login ID.
Hopefully, this helps you in trying to understand why a user might not be able to get logged in.