How did I make a checkered pattern within a cell in Crystal Reports cross-tab?

Question

I think I am pretty good at Crystal Reports since I use it all the time. So I have a reasonably advanced report that has a cross-tab and somehow I ended up with a checkerboard pattern within one of the cells. I've never seen this before and didn't know it was possible! I would like the cell to be white. If anyone can explain what I did wrong, I would be grateful!

So within the cross-tab I have two different summaries but I'm trying to hide that, that's why it looks like there is a white vertical line in the cells. My columns are grouped by year then month, then by date so there are some subtotals I'm hiding.

The cells are formatted via Format Field; they have the same formula for both summaries:

if gridvalueat(currentrowindex,currentcolumnindex,1) > 1 then rgb(224, 114, 177) // pink
else if gridvalueat(currentrowindex,currentcolumnindex,1) = 1 then rgb(105, 192, 98) // green
else if gridvalueat(currentrowindex,currentcolumnindex,0) = "a" then rgb(255, 231, 63) // yellow
else if currentcolumnindex = getnumcolumns-4 then crwhite // there was some error where cells were showing up yellow if they were in the last column, so this is my fix for that
else if gridvalueat(currentrowindex,currentcolumnindex+1,0) = "a" then rgb(255, 231, 63) // yellow
else crwhite

Happy to answer other questions if I didn't give enough information!