Cooling problem, I'm stumped!

[Bmwe5320023.0]

In the past few weeks/months, I've been getting a low coolant message. I drive the vehicle very little for the most part, so I was just adding coolant every few weeks.
Yes at the same time, I've taken the vehicle on 500km trips, so i know for sure the leak wasnt too bad, or i wouldn't have made it without adding coolant during the trip, which i did not do.

The vehicle wasn't overheating, and I didn't see any leaks, so I thought maybe the engine is taking a little hit of coolant.

But 2 days ago I had my X5 2002 3.0 (M54) overheat badly.
I traced the problem to the lower radiator hose, because I could see the coolant leaking from there.

The factory clamp of the lower hose came partially off, and the coolant was leaking so bad I went through 5 gallons of coolant in 10 minutes.
Luckily I found a Napa store nearby, and put a clamp on top, which allowed me to get home. With a pit spot in between, to cool off and add more coolant to the system.

At home I removed the factory clamps, and installed my own clamps.
No more leaks.
I thought I was done with what was an easy fix.

No quite....

As soon as I started driving it kept overhearing again, and the coolant was going somewhere, disappearing.
I checked, no coolant in the oil, no smoke from the pipe, nothing leaking from under the car.

I bled the system, even parked it at a steep angle, and set the heater on 32C degrees and lowest fan setting.

I noticed something happened with the red floating level in the expansion tank. Somehow it came out of its orbit, so it wasn't centered. But then it disappeared completely, even when the expansion tank is full.
It must've stuck somewhere.

I'm really stumped by this we I've fully replace the coolant system within last 15k km

The other thing that happened when X5 overheated a couple of days ago, the active cruise control light came on the dash and is still there lol

All the hoses are hot to the touch, so I assume the coolant is making its way through the radiator, which means that the thermostat is good then?

I really don't understand where the coolant keeps disappearing. On a 30 minute drive, I have to stop 3 times to cool off the vehicle, open the expansion cap, and add a good few liters of coolant.

I have 1.4 bar cap from E34, which means the system will vent sooner if it overheats.
Never had any problems because of it before, neither with E39 not 53.

I can't figure out where the coolant is disappearing and why I can't drive the vehicle for more than 10 minutes without overhearing.

I'm watching the temperature live, and it just keeps going up until 125 where it just gives a massive warning. I try to turn off the vehicle before that and cool it off.

This is just driving me nuts