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Does the listFile exhibit the same behavior or does it list your file correctly? - The fact that the logs shows it the processor yielding tells me it found no work to do (meaning no files to list). It yields so that it does not consume not stop CPU looking for work that does not exist.
Did you check your properties for leading or trailing whitespace? Did you try removing the "\" from your file filter?
You may also want to verify your processor configuration for both input directory and file filter to make sure you do not have any leading or trailing spaces. Spaces are treated as valid characters to NiFi which can result in NiFi not finding the file or even the directory.
Are your files still in the source directory? GetFile defaults to removing the files you specify, so if something went wrong you might not have those files anymore, you'd need to set Keep Source File to true in that case (as Matt Clarke recommended). That's why the recommended option is ListFile->FetchFile, as it will keep track of the files it's seen and not fetch those again.