I have this error when trying to create a Parting Line: "Rebuild Errors - You must select edges that form a closed chain." And the screen looks like the image attached.

I have been trying to select the front plane but it does not recognize it as a "closed chain". How can I create a nice curved line around my part at the front plane? It may be an issue that the main body and each extruded cylinder around the outside (there are 6, equally spaced) read as different entities.

Thank you!