I'm moving mailboxes from exchange 2010 to 2016. environment is co-existence mode. I moved a single mailbox with no issues and cut it over to 2016. I then batch moved 4 mailboxes and set then to no complete at 95% so that I can complete the batch when ready. this is also fine. while those are synced at 95% I'm attempting to to move another single mailbox and it started moving but then stalled at 20% for about an hour with a status of "stalled due to target_processor". resources are fine and so is CPU. I looked at the migration report and there are no failures or errors and all processes, initializations, and prep for the migration is fine. No errors in the eventlogs either about this. Has anyone seen this? I haven't changed any throttling or anything.