Strong correlation of what for X_1.fastq? You're leaving out a lot of required context here. --split-files is just going by what was submitted, so if the people who created the dataset screwed things up then you'll get screwed up results.

I am happy both posts are closed, the question is not that useful to others. So...

You should have simply closed the post using the edit feature rather than wiping out everything. This way others could still see the question. Even though you have got your answer, the post could have helped other people who may come across the same problem in future.

Hello zhwjmch!

OP removed post contents once their problem was solved. OP doesn't understand how forums work :(.

For this reason we you have closed your question.

If you disagree please tell us why in a reply below, we'll be happy to talk about it.

Cheers!

I would like the OP to imagine the usefulness of this site if everyone did what the OP has done: remove their question's content once it is answered ...

Short answer: removing content once answered is considered inappropriate course of action.