Can you post a screenshot of what the C1 Session folder hierarchy looks like?
That may not be as simple as it sounds. The term "C1 Session folder" is probably a good start because it exists on disk. A session has a name, "MySession",say. By default, the name of the Session folder reflects the sesson name. That is not set in stone though, but MySession will normally be in a session folder MySession somewhere in a path on disk, say /home/users/username/images/captureone/sessions/MySession.
The most prominent member in the MySession folder is a session database file (SQLite3). The database file will (by default) be MySession.cosessiondb if we continue along the same line. There may be, and typically are 4 sub folders in the MySession folder. They are Capture, Selects, Output and Trash in the English language GUI. If we think of the session folder MySession as a root in the file system, it looks like
MySession/
Capture/
Selects/
Output/
Trash/
MySession.cosessiondb
The C1 GUI has a "Session Folders section". That section lists (by default) the 4 folder names "Capture", "Selects", "Output" and "Trash". It has confused many C1 users to believe that they are the actual disk folders, but no, they are virtual folders/links/pointers. The user can navigate to any folder on disk and make it become the sessions's "Capture", "Selects", "Output" or "Trash". All 4 may link/point to one common folder on disk. It is just a happy or perhaps unhappy coincidence that the GUI Session folder "Capture" by default points to a disk folder named Capture inside the MySession disk folder.
C1 session users that swear by the "dummy session" technique, exploit this to their maximum benefit, they may have just one DummySession represented by a MyOnlySession folder for a SQLite3 SomethingElse.cosessiondb and images spread all over their storage media space. Then there are Session Favorite folders on disk.
C1 processing circles around functionality related to predefined sub folder names (Capture, Selects, Output, Trash) in a session's folder, but they may or may not exist on disk and may or may not be in the expected location.
My advice would be to investigate closely and get in touch with PhaseOne/CaptureOne before you begin :-)