Replace Color turns objects black if new color is not opaque

When I select either an object or multiple objects, then open the "Replace color" from the Extensions > Color menu - after inputting the color I want to replace (I've tried using the color picker and the result is the same) - when I try selecting a new color, the obect(s) turn black.

Upon further investigation the color being chosen seems to have a problem. When I cut and paste the color output into the RGBA box and tried running a simple text replace on the raw SVG, all of the objects turned black again. I think it's due to an invalid color. When I used "#ff0000" instead, the object turned red.

Would be nice if you included a simple hex color chooser in your replacer.