Problems with Bounces and Complaints from Amazon SES

Your software
My Mautic version is: 3.3.2
My PHP version is: 7.4.20
My Database type and version is:

Your problem
My problem is:
I have problems with the Webhook receiving from Amazon SES the bounces and complaints. It is all properly configured, but sometimes the requests are processed and sometimes not. It is kind of like lottery. For now I get the complaints all by email and check one by one whether they were processed. No clear pattern on which requests are recognized and which ones are not.

Did you have any errors saying ‘payload not recognised?’

Where shall I look for this error? There is nothing in the notification, except of the upgrade message, and today’s error log is empty as well.

Can you plz look in your daily logs (some previous days) in /var/logs ?

I find some errors related to campaigns, broadcasts and segments, something related to a file not found in the SQL driver.

I got once the following error:
[2021-06-10 15:53:41] mautic.CRITICAL: Uncaught PHP Exception Symfony\Component\Debug\Exception\ClassNotFoundException: “Attempted to load class “EmailLexer” from namespace “Egulias\EmailValidator”. Did you forget a “use” statement for another namespace?” at /home/customer/www/ line 27 {“exception”:"[object] (Symfony\Component\Debug\Exception\ClassNotFoundException(code: 0): Attempted to load class “EmailLexer” from namespace “Egulias\EmailValidator”.\nDid you forget a “use” statement for another namespace? at /home/customer/www/"}

At the same day there was one error communicating with AWS in the email:send command:
[2021-06-10 23:26:08] mautic.NOTICE: Aws\SesV2\Exception\SesV2Exception: Error executing “GetAccount” on “”; AWS HTTP error: Server error: GET resulted in a 500 Internal Server Error response: {“message”:“An internal failure has occurred.”} InternalFailure (server): An internal failure has occurred. - {“message”:“An internal failure has occurred.”}

Once in a while there is a clickthrough error or other things irrelevant.

Hello, did you fix it?

seems that hard bounces are now processing correctly, without me changing anything in the configuration. I have still a problem with unsubscribe request coming via email. Sometimes they are not getting processed correctly, and I double check whether they were marked correctly.