Not all form completions are showing in Mautic

Your software
My Mautic version is: 2.15.1
My PHP version is: 7.0.33

Your problem
My problem is: Visitors are completing a mautic form on a wordpress website. Some of the form completions are not showing in mautic when looking at the form completion records. The record is saved to mautic and actions are triggered, but they do not appear in the list of form completions.

These errors are showing in the log:
[2020-01-30 06:31:22] mautic.NOTICE: Doctrine\DBAL\Exception\ConnectionException: An exception occured in driver: SQLSTATE[HY000] [2002] Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock’ (2) (uncaught exception) at *****vendor/doctrine/dbal/lib/Doctrine/DBAL/Driver/AbstractMySQLDriver.php line 103 while running console command mautic:segments:update

I don’t think this error is related.

Steps I have tried to fix the problem: Checked that all form fields are set to “save result”. Completed the form myself and all wors as expected. Issue is inconsistent it seems.