Custom Sizes greater than 720pxl

I'm trying to convert images to a specific size - 1280 pixels. I can select a preset resize in percentage, but if I select "Custom Size" and type in ANY number greater than 720, all I get is 720 pixels wide. All the "Reduce to nn%" work ok, so I can end up with pictures 1500 pxl wide as nearest to what I'm really after. Is the "Resize | Custom Size" broken?

Screen image of Convert Image" window below:

Because the Preserve aspect ratio option is on Opus will take the dimensions you supply and then adjust them to, well, preserve the aspect ratio.

If you want the size to be exactly 1280 pixels wide, leave the height field empty and Opus will calculate it automatically. Or, turn off Preserve aspect ratio and then it'll use the exact dimensions you supply.

Thanks, that fixed it. It was the first time I'd used the Convert Feature; it didn't click with me that I had to leave the second field blank, assuming that, like in both Paintshop and Photoshop, changing one parameter whilst having "Preserve Aspect Ratio" set, automatically altered the other. Anyway, all sorted now.

The way it works allows the option of specifying both dimensions when batch-processing multiple images of different aspect ratios, where Opus will fit them all into a that size (say 1280x720 so they all fit 1:1 on a particular display device) while maintaining their individual aspects.