Mst: Preorder + Back in stock

This app used to work well but since the update to "version 3.0" - it continuously fails. We have to remember to check on it and every time we do, it is not loading on out of stock products - the developer has to go in and change something but never explains what and never makes a permanent fix. It seems they have introduced a recurring catastrophic error and are unable to fix it. The best answer we have had is "It is a coding issue, I have fixed it" - but then it breaks again a few weeks later.