Excel Report Writer adding empty columns?

Haven't worked with Pipeline Pilot for a while and just came back. I built a simple protocol that will generate tables whose column count and row count are based on user input (e.g. number of group etc.). Didn't do any fancy formatting, mainly pretty basic setting. The report was generated fine and can be write out in exact same format by either HTML Report Writer or PDF Report Writer. However, if I try with Excel Report Writer, when I open the file, I would get a bunch of empty columns in between my data columns (seeming empty column count equals to number of rows - 1 in current table), although all the data would be there correctly. Did a search in community but didn't seem to find similar topic. Anyone ran into this or could offer any hint? Thanks!