Join two csv files by matching columns, join command

I have two .csv files that I need to match based on column 1. The two file structures look like this. FILE1 gopAga1_00004004-RA,1122.825534, -2.497919969, 0.411529843 gopAga1_00010932-RA,440.485381, 1.769511316, 0.312853434 gopAga1_00007012-RA, 13.37565185, -1.973108929, 0.380227982 etc... FILE2 gopAga1_00004004-RA, ENSACAP00000013845 gopAga1_00009937-RA, ENSACAP00000000905 gopAga1_00010932-RA, ENSACAP00000003279 gopAga1_00000875-RA, ENSACAP00000000296 gopAga1_00010837-RA, ENSACAP00000011919 gopAga1_00007012-RA, ENSACAP00000012682 gopAga1_00017831-RA, ENSACAP00000016147 gopAga1_00005588-RA, ENSACAP00000011117 etc.. This is my current command that I am running using join: This is formatted from what I have also read on the following threads here join -1 1 -2 1 -t , -a 1 -e "NA" -o "2.2,1.1,1.2,1.3" output.txt However, every time I run this prompt it only writes the first row to output. Anyone know why my code is running like this and not actually merging the two files based on the GOP ID?