I’ve been having that issue where torch takes off before it fires. Im using the Miller 625, so not sure about the HT45xp, but I had to add some delay after my cuts to let the torch ‘reset / cool’ before the next pierce. I modified the fusion360 post to give me some options to add delay. Link to the thread about that below…not sure if same issue, but definitely messed up a bunch of cuts before I realized what was happening.