Unable to open Sync feature?

Hi there Tabox! I am loving this program and it has been a lifesaver for someone who bounces around a lot of devices for work reasons.

I have lately been getting an error where I am unable to open the sync window on one of my devices. I will try to reinstall etc, but was wondering if you might know what it could be?

Sync feature has been working prior but stopped in the last two months, so I have been exporting out the sites.