2023 Clubman + Dog-guard question

[Yertis]

My wife has bought herself a Clubman and it came with a dog-guard, which is secured using the lugs which also fasten the the rear seats into the upright position. Everything was fine until the other day when she had to move the back seats back to the normal 'reclined' position for passengers. When she returned the seats to the upright position (for max dog-space) the dog-guard was loose and flops back-and-forth. I've been roped in to fix this because I "know about this sort of thing" but cannot see how the guard was secure in the first place. Anyone have any clues?