If you use Sucuri for WordPress, your WooCommerce API may be getting blocked when Fomo attempts to access order data.
Here is how you can whitelist Fomo.
Step 1
Go to the Audit trails and see what is being blocked. Look through the logs for a path starting with wp-json/wc/v3, wp-json/wc/v2 or wp-json/wc/v1.
Step 2
Once confirmed, visit Settings > Access Control > Whitelisted Url paths and enter the blocked path. The blocked path in this case may be /wp-json/wc/v3/ or /wp-json/wc/v2/ or /wp-json/wc/v1/.
Step 3
You're done! Fomo should now play nicely with your Sucuri firewall.