AT can be a bit temperamental, when I first tried it I couldn't get it to solve out-of-the-box.
If you have downloaded the correct plate sources, the only parameters you really need to worry about are --sigma and scale max/scale min. Increasing the sigma speeds up solving time but at the expense of accuracy. Once you've got it solving, you can tweak the search radius and scale max/scale min to gain some speedup.
If you feel like uploading a sample of what you want to solve I'd be happy to run it through AT and have a look for you.
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