Invoice number progression

Hello,

I’m using your plugin combined with WooCommerce PDF Invoice Italian Add-on.

I just noticed that the numeration is messed up: it should progress normally from 1 to 9999, but it seems to have two numerations at the same time.

For exemple: it goes from 0111 to 0118 normally, then suddenly puts a 0013, it goes on with 0119 to 0121, and then 0012, 0011… it doesn’t makes sense to me. And it happened multiple times that it restarted apparentely randomly, despite the fact it’s programmed to restart every year.

Can you help me?