Mailbox Settings
-DeleteComments The DeleteComments parameter specifies whether to remove or keep any text in the message body of incoming meeting requests. Valid values are: $true: Remove any text in the message body of incoming meeting requests. This is the default value. $false: Preserve any text in the message body of incoming meeting requests. This parameter is used only on resource mailboxes where the AutomateProcessing parameter is set to AutoAccept. Please check if -DeleteComments is set to true, if yes then it needs to be changed to false.
https://docs.microsoft.com/en-us/powershell/module/exchange/set-calendarprocessing?view=exchange-ps Additionally ensure that the meeting invite after it auto accepts - is present in the inbox and not sent to deleted items