I am having a similar issue. I have a few.tiff files in my map, all of which have a pre-defined color ramp. I need to change one value in all .tiffs to be null. However, no options appear to alter color when I click on the, in this case, green symbol box. I can only change the label of this green color.
Any ideas? Thanks!
Ditto. I have a basemap .tiff file with a pre-defined colormap. I would like to change the colormap value = 1 (currently white) to no fill. This is a simple task in ArcMap but seems to have disappeared in Pro.
We've found a work around. First, bring in your .tiff file. Under symbology select the hamburger button at the top right and select "export colormap". Then, like Amelie said, under Primary Symbology we changed it to "Unique Values". This will then set a random color to all raster values, which is not what we want. However, from there you can import the color map layer you just created by selecting the hamburger button at the top right corner, select "import colormap", and select the .clr you just created (you may have to click refresh for it to pop up). From here you have the control to null out what ever value you want since now it is a unique value.