8-bit raster images with pixel values greater than 50% of the max (i.e. 124/125 of 255) receive a failed error when applying a colormap.

Solución alternativa

Apply the colormap through the Symbology pane.

Open the Symbology pane for 'MoreThan50_8bit.tif' > Change Primary symbology to Unique Values (when adding the colormap now that the value symbology is similar to the colormap values, the tool still fails) > Select the Options icon > Import Colormap > Navigate and select desired colormap.

Pasos para reproducir