I can confirm our Timezone settings, clock and date were, and still are, all correct, but this was my first thought too.
You mention in the changelog of the plugin that the Auto Coupon feature had been rewritten, may I ask why? Were there any problems with it? Anything that could be related to this?
We were running version 3.0.4 when we ran into issues, as of this morning (UK Time) we are now on the latest version.
As for the issue we experienced, whilst it looks resolved now, we would still like to understand what is happening in the background so we can best prevent ourselves from running into it in the future.
In the meantime, I’ll speak with Automattic and see what they can tell me about this, I’ll share any findings.