I have spent the last week working with Mailchimp to troubleshoot the MailChimp for Salesforce plugin, which is no loner syncing contacts from Salesforce onto our MailChimp list. MailChimp tech support has requested information from Salesforce Support in order to proceed with the troubleshooting. As a standard customer, I have been told the only way to access any support is through this forum, so I am hoping someone has insight!

What we know:
• Users of the MailChimp for Salesforce integration are experiencing an error that “a batch job is already in process”.
• From what we can see, these batch jobs are in a ‘holding’ state in the Apex flex queue, and are never moved to the Apex job queue for processing.
• In order to protect org resources, MailChimp integration will not start a second batch job if a MC4SF batch is already in the apex queue.
• We have established that there are no other apex jobs currently running that would cause the hold in the flex queue.
• Since we can verify that these batch jobs are being created successfully, the issue appears to be with how they are being handled for processing in these queues, which is a function controlled exclusively by Salesforce.

MailChimp support has asked me to find out:
• What could cause a job to remain in a ‘holding’ state in the flex queue?
• Is there anything that would prevent a batch job from being able to move from the flex queue to the job queue?
• Is there anything unique to this specific org or the Apex flex queue that would prevent these jobs from running as expected?