I just completed all the side-ops in MGSV. As discussed in this post some side-ops light up again after you complete them so you can always do a side-op again even after completing all of them. However there is a challenge task, "complete all side-ops" that I would like to check off. But even though I have completed all the side-ops there is a caption in the lower right of the side-ops list that says "Completion 135/157".
How do I finish all the side-ops?