In this thread How to use BlurXTerminator with AutoIntegrate? - #68 by Gazz1 Garth explains that MacOS by default always scales the images to 1680 x 1050 on native screen even though the resolution could be a lot higher. That could be one source of problems. But the preview size in your case is 333 x 333 so it should fit even if the screen is scaled to 1680 x 1050.
I have added some (hopefully better) automatic scaling but only when the script is started for the first time. I would not like to mess with any settings already saved as they may be saved by the user.
I had increased the minimum size for the file list. Possibly that could be one source of problems. I have reverted that back to the old setting.
I am a bit out of ideas right now. I have some minor changes that I have pushed out as 1.64 test5. Maybe they help, maybe not.
Jarmo