I use obisplit to spilt a fastq file. I would like the output sequences to be in upper case, but the --uppercase option doesn't work.

My command is: obisplit -t sample --uppercase file.fastq

I checked the "file.fastq", sequences are in upper case. The sequences in output files are all in lower case. Is there anything wrong with my command? I also tried obisplit -t sample file.fastq --uppercase

BTW, the --uppercase option works for ngsfilter.