It depends on the format of the audio file. The term loop does not have a precise definition. Sometimes a plain wave file is called a loop. Acidized waves are also called loops. When a plain wave file is played in Session Drummer, it plays one time. When a wave file plays continuously in Session Drummer the file has a loop in it. I have no idea what files you are working with and can only describe what happens when different types of files are played in Session Drummer.
It does seem odd that the "Hit Files" repeat, if they are intended to play as one shot files. It may be something to discuss with the CD manufacturer.
Files can be converted to plain wave files in a audio editor. Some editors can work on batches of files. An editor can also the loops points, if any, in a wave. If you don't already have a commercial editor like SoundForge or Wavelab, a free editor like
Wavosaur would work.