@malllory.woods I've not had the issue but looks like this could work (https://poi.apache.org/apidocs/dev/org/apache/poi/ss/usermodel/FillPatternType.html#SOLID_FOREGROUND)?

<cfset FillPatternType = createObject("java","<http://org.apache.poi.ss|org.apache.poi.ss>.usermodel.FillPatternType")/>

<cfset cellStyleBGYellow.setFillPattern(FillPatternType.SOLID_FOREGROUND)/>