Any idea for the reason why the transaction log shipping is out of sync after my maintenance plan ?

no this is the only bakcup FULL that is performed, the one from the maintenance plan.

it used to work fine since many month but now i am getting this issue...

here it is... sorry : the image was showing fine on my computer so i thought everybody could see it

done

here is my maintenance plan :

is a skrink database may cause the issue ?

I got the same issue.

I have setup a full backup (part of a maintenance plan) on a daily basis at midnight + running a transaction log shipping every 15 min...