Formatting numbers with openxlsx package in R

Question

I am trying to format certain columns using openxlsx to write an r data frame to an excel file.

Here is a snippet of the R data frame:

The square bracket part in the "seed" column is used to superscript the excel output.

Here is the code I used to write the file:

openxlsx::addWorksheet(wb, sheetName = 'data') # add sheet

openxlsx::writeData(wb, sheet ='data', 
                    x=df, xy=c(1, 1),withFilter = T) # write data on workbook

# make quality codes superscript
for(i in grep("\\_\\[([A-z0-9\\s]*)\\]", wb$sharedStrings)){
  # if empty string in superscript notation, then just remove the superscript notation
  if(grepl("\\_\\[\\]", wb$sharedStrings[[i]])){
    wb$sharedStrings[[i]] <- gsub("\\_\\[\\]", "", wb$sharedStrings[[i]])
    next # skip to next iteration
  }
  
  # insert additional formatting in shared string
  wb$sharedStrings[[i]] <- gsub("<si>", "<si><r>", gsub("</si>", "</r></si>", wb$sharedStrings[[i]]))
  
  # find the "_[...]" pattern, remove brackets and udnerline and enclose the text with superscript format
  wb$sharedStrings[[i]] <- gsub("\\_\\[([A-z0-9\\s]*)\\]",
                                "</t></r><r><rPr><vertAlign val=\"superscript\"/></rPr><t xml:space=\"preserve\">\\1</t></r><r><t xml:space=\"preserve\">",
                                wb$sharedStrings[[i]])
}

openxlsx::modifyBaseFont(wb, fontSize = 10, fontName = 'Arial')

# right-justify data
openxlsx::addStyle(wb, sheet = 'data', 
         style = openxlsx::createStyle(halign = "right"), rows = 1:nrow(df)+1, cols = 3:12, gridExpand = TRUE)

#apply to rows with "All" in column B
openxlsx::conditionalFormatting(wb,sheet = 'data',
                      cols = 1:ncol(df), 
                      rows = 1:nrow(df)+1,
                      rule = 'LEFT($B2,3)="ALL"',
                      style = openxlsx::createStyle(textDecoration = 'bold', bgFill = '#dad9d9'))

# format numbers
openxlsx::addStyle(wb = wb, sheet = 'data', 
                   style = openxlsx::createStyle(numFmt = "#,###.0"), 
                   rows = 1:nrow(df)+1, cols = c(5:7,10:12),gridExpand = T)

# write excel file
openxlsx::saveWorkbook(wb, file="file.xlsx", 
                       overwrite = TRUE)

The output looks like this:

I am trying to conditionally format the numbers in the seed/harv/yield/prod columns to be numbers, but the "F" values are creating a mixed-class vector at best. (I need these Fs!)

Any ideas?

Thanks!