Not much wrong with your rig,but here's what I do.
1.I would make it a combi-link,a stiff boom section of 20-25cm,with only a 2-3cm soft braid section,and add a small 3mm shrink tube kicker on the hook eye.Add a large lump of tunsten putty where the stiff and soft section meets.
2.Move the tubing on the shank up over the bend of the hook,to right above the point.That transfers the weight of the bait to the hook point,helps it to turn over quicker.
3.That is a large bait,I would make the gap between the bait and the hook bend at least 10-15mm.That separation is needed to allow free movement of the hook.
That being said,this rig needs to tighten against the lead to make it 'flip and turn'.If the fish are feeding cautiously,they might not pick up a heavy bottom bait.The same might happen if you are feeding particles around this rig,they move very slowly when feeding on particles.For this rig to be at it's most effective,you need them feeding aggressively and moving quickly.
The rig I described above is known as the 'claw rig',or advanced bottom bait rig.It needs to be used in the right situation.I use it when feeding a wide spread of large boilies on a hard bottom,such as clean sand,gravel or clay.When feeding smaller baits such as particles or pellets,I would use a balanced bait on a blowback rig,much easier for fish to pick up.
Lastly,if your venue has lots of small fish,that might also cause missed bites,they might be too small to fit that large bait into their mouth.So they only pick up the bait and not the hook.I learned this when fishing the Vaal river,muddies love boilies but they have very small mouths.Drove me insane until I figured it out,caught one by accident after about 50 missed bites.Hooked behind the head.
There are a lot of small carp where I fish, hence trying with this big bait. I've been catching 2kg carp with 15mm popups, so I thought about stepping it up. I will for sure make my hair a bit longer as per your suggestion, thank you Beeslek.