Rowspan not working when ^ is in last column

This is a great filter module that makes it really easy to create a complex table (and edit it again later without getting too lost). However, when I try to have a rowspan in the last column, the filter leaves the "^", rather than creating the rowspan. I had a quick look at the module code to see if I could spot where this is happening, but I got lost going through all that $j=$k code....I'm still relatively new to PHP.