Seems to have the same issue. 17 600 orders with status completed. Is that the information the plugin is trying to sync? In progress has been the status for 15 minutes now.
Some info from Status log.
### WordPress Environment ###
WC Version: 2.6.8
Log Directory Writable: ?
WP Version: 4.6.1
WP Multisite: –
WP Memory Limit: 1 GB
WP Debug Mode: ?
WP Cron: ?
Language: sv_SE
### Server Environment ###
Server Info: nginx/1.10.0
PHP Version: 7.0.13-1+deb.sury.org~trusty+1
PHP Post Max Size: 100 MB
PHP Time Limit: -1
PHP Max Input Vars: 3000
cURL Version: 7.35.0
OpenSSL/1.0.1f
SUHOSIN Installed: –
Max Upload Size: 100 MB
Default Timezone is UTC: ?
fsockopen/cURL: ?
SoapClient: ?
DOMDocument: ?
GZip: ?
Multibyte String: ?
Remote Post: ?
Remote Get: ?
### Database ###
WC Database Version: 2.6.8
### API ###
API Enabled: ?
### Theme ###
Child Theme: ?
Parent Theme Name: Flatsome
Parent Theme Version: 2.8.5
WooCommerce Support: ?