Suddenly my color gradient palette is missing when editing sprites

When I attempt to edit sprites in Construct 3, now the square area that shows the rainbow color gradient is an empty white square. I can only either use the eye-dropper tool to select pre-existing colors in an imported sprite, manually change the RGB number values, and use the dark/light slider. This started happening as of today. The other day the gradient was still there. Not sure if I turned off an option or something but this has persisted no matter what I try to do, and I haven't been able to find a solution on Google. Thanks!

Drag here with mouse:

Drag here with mouse:

The issue wasn't the custom colors, it was the fact that the area directly above that (the sort of rainbowy gradient zone) had turned pure white. Whatever had happened, it sorted itself out, though. Thank you!

If you drag that line below the custom colors, this will move/resize the rainbowy gradient area.