Scheduled Grid Migrations are experiencing extended downtime

This issue is now resolved.
Current status and actions being taken: We identified database write throttling as the cause of the stalled grid migrations. We applied a drop rule for jobs that were stuck in a retry loop, which has restored normal migration processing. 
Scope: A small number of enterprise users undergoing grid migrations experienced extended delays in accessing Slack. 
Current impact to end users: Affected users may have experienced an inability to access Slack during their migration window. 
Known workarounds: No workarounds needed at this time.
We apologize for how this incident affected you and your business. 

Users who are undergoing scheduled Grid Migrations are experiencing extended downtime. Downtime is expected during a Grid Migration however it's taking longer than usual. During the downtime users are unable to access Slack until the migration completes. We've identified an issue with Job Queues, which may be the cause and are investigating this further. The next update will be provided once additional information becomes available.