Match Service Broken

As a background context I must say, the service was working pretty fine the first 2 times I used with two different files.
Problem was I started uploading my 3rd csv, on the match service section (pre_unique - part3.csv).

Later on, when the upload is finished it prompts me to this section, in which I can handle the headers on the right way:

So once I click on next button I wait for the next screen

But it prompts me to the first screen

I thought maybe the file was corrupted. So I decided to try again with the two files that I processed 1 day ago. And it failed the same way. Anyone having the same problem? Thanks in advance.