Abandoned cart emails in Shopify

There is a glitch on some Shopify stores in the Abandoned cart notifications.
To check if this is happening to you, go to admin/settings/notifications, and click into Abandoned Cart. If you see the message "Body is missing the {{ custom_message }} drop." then your abandonment messages are probably scrambled.

I've followed up with Shopify on a global fix for this and they are working on it, but if you want to fix it in the meantime, copy and paste your current message somewhere safe (in a text doc) and click on the 'revert to default' button at the bottom and save. You can preview the result from the drop down under the '...' button at the top right.