After a successful trial we have resumed all deliveries to Ireland (Republic) with immediate effect.

We still don’t know what the issue was as we haven’t changed our processes, but Royal Mail and AnPost seemed to have sorted their issues.

Previously, more than 50% of our orders were being rejected by AnPost despite all our orders having the correct paperwork and we made the difficult decision to suspend all deliveries.

We weren’t alone in experiencing this issue (Examples: 1, 2, 3, 4, 5).

Further sources:

Irish Times
Irish Mirror
eBay community forums
Reddit
Etsy community forums