TCC: (Sys) The process cannot access the file because it is being used by another process.

[Quatrix]

I'm trying to use the variable function %@LINE[file,n] to read a certain line from a log file that's currently open by another process, but it gives me the error shown in the subject line. This is a passive read function that doesn't write anything to the file, so I don't understand what the problem is. I'm able to open the file in Notepad, view the contents using TYPE, copy the file elsewhere in Explorer, read the file inside a Java program, etc.