Through the prepare, I use the replace functionality on a column to replace all empty cells with "0" but it only worked for a small % of cells.
It seemed like a known issue before. Is there a workaround ?
You can try using a formula processor with the following formula:
if(columnname == '', 0, columnname)
It would also be good to check if you have any spaces instead of empty values and try to replace those with '0' as well. The formula for that would be
if(columnname == ' ', 0, columnname)