I don't understand, there is really something strange.
I entered the tickets created by you as "test" (IDs = 7227,7228,7229), I tried to download the files you attached with extension "php", I could not download any files.
I have activated the incognito mode. I performed the same test and managed to download all your files and also those of the tichet with the name "sdfsdfsdf" with ID = 7225.
So I went back to normal session, I logged out, I came back as administrator, same problem.
So I decide to try again in incognito mode .... incredibly even here it doesn't work now!
There seems to be an intertwining with sessions, cookies, something.
Because in the various attempts at a certain point I seemed to see the user name of the test user "ETP" at the top, but even when it says "ADMIN", it is as if the permissions to access that file are denied because the user does not have them.
I'm going crazy, at first I thought it was a file extension problem, instead there is no distinction between your PHP files and those sent by my clients (usually .ori, .mod, .bin).
The error is random and happens a few times in one ticket, other times in another. Both in incognito mode and in normal mode.