CRON Messages: In Mailbox.php line 542

Your software
My Mautic version is: 4.4.5
My PHP version is: 7.4
My Database type and version is: 10.3.36-MariaDB-0+deb10u2 - pdo_mysql

Your problem
My problem is:

These errors are showing in the log: CRON Log full of “CRON Messages: In Mailbox.php line 542” messages:

In Mailbox.php line 542:
  Attempted to call function "imap_search" from namespace "Mautic\EmailBundle\MonitoredEmail".

mautic:email:fetch [-m|--message-limit [MESSAGE-LIMIT]] [-h|--help] [-q|--quiet]
[-v|vv|vvv|--verbose] [-V|--version] [--ansi] [--no-ansi] [-n|--no-interaction] [-e|--env
ENV] [--no-debug] [--] <command>

Steps I have tried to fix the problem:

Verified PHP IMAP installed and working (also works on other sites on this server).

Cron Job:

php /path-to-mautic/bin/console mautic:email:fetch

We tried several combinations in the “Monitored Inbox Settings”:

With nothing set in “Bounces”, “Unsubscribe Requests” or “Contact Replies” the cron job returns:

No mailboxes are configured.