[EDIT#1]
And a stupid, beginner's mistake: not using the "Search" before posting.... really sorry about this
[/EDIT#1]
[EDIT#2]
After reading above---^^^ run the pam_tally2 as root:
sudo pam_tally2 --reset and the counter was reseted running in omv-firstaid:
No locked/banned users or candidates exists.@Moderators: Feel free to delete or leave the thread if you think it's beneficial to anyone, 
[/EDIT#2]
1st issue posted 
Never had configured the mail notifications, but finally decided to.
Started receiving a info about "Locked users overview" and that to reset the counter, to use omv-firstaid.
Fired the terminal and launched it (I don't recall ever using it, nice tool to start discovering with EXTREME CAUTION).
Scrolled down to #4 and clicked "OK" but it errored out.
Tried with sudo omv-firstaid and the same issue.
Here is the log to it to see if anyone has an idea of what's wrong:
Reset failed login attempt counter for user '[NONAME]'.
pam_tally2: pam_get_uid; no such user [NONAME]
pam_tally2: Unknown user
ERROR: Command '['pam_tally2', '--quiet', '--reset=0', '--user', '[NONAME]']' returned non-zero exit status 1.If any info more is helpfull, please, let me know.
Thank you in advance