Issue Manually Running Sync

I’ve got a weird issue. I’ve got a sync project that is scheduled to run each evening. The sync runs fine during its scheduled run. However, if I try to manually run the sync, by calling up the project, and using the “Sync Now” button, it errors out with an “Object reference not set to an instance of an object.” (Screenshot below). I can open up an individual item, and run the preview just fine. But as soon as I try to sync, it fails. But again, it only does this if I try to use the “Sync Now”. If I let the job run as scheduled, it syncs fine. I’m currently running 8.0.20 of Sync, but this issue has persisted through several versions.

Anyone else seen an issue like this?