Hi, this issue is also happening in 1.2 and also 1.3.
If you spawn in and selecting the weapon from your back, the IK is not set correctly. This will also make your scope rotating on Y axis and is not staight. You need to call any weapon command, to reset the IK, like lowering and raise again.
This also happens if you jump over, after the jump the IK will also not reset and you need to crouch or lower to call a IK reset.