For anyone who cares… here is the response I received from support:
“Thanks for the follow-up question, happy to address it. When a list has not finished processing, inaccurate list numbers may be utilised in other assets where the list is being used, such as reports, workflows, marketing emails, etc. Lists typically finish processing in 5-7 minutes but in some cases, we can unfortunately see delays of up to a few hours. Definitely understand the inconvenience that this causes, and I’d like to confirm that the Product Team is aware of this pain point, and are looking to implement a more robust and efficient list processing system in the near future.”
So apparently it is not an urgent matter for Hubspot to notify users about or rectify a problem that is causing users to send emails to and trigger workflows based on lists where the interface indicates list processing is complete but it actually is not for up to “a few hours.” SMH. Unbelievable. I don’t know how people trust this system, it is a real s!#* show.