Roof Hoop bolt loose

[Wiz]

Noticed the other day that the ns roof hoop bolt is loose. Tried tightening up and it just turns, seems fairly secure but isn't tightening.
Are these meant to be like this, is there a locking nut on the other side to allow the hoop to move?

[Wiz]

Thanks for the quick replies

Have just had the roof panels off and checked the other side which is the same. More pronounced with the stays down. Seeing the nyloc in the pictures suggests it's meant to move. quite a bit of movement round the bolt though. Guess it could be to allow a bit of give when opening/closing or could just be a bit of wear.