F-Coolant Loss

[Bobbilljim]

I Last year I bought a 2017 v6 form an JLR main dealer after 6 months it started loosing coolant from the expansion bottle which eventually led to a head gaskit issue and new engine replacement fortunately under warranty. 4000 miles on and I’m starting to see a similar issue with small leaks from the bottle and a smell of coolant when k turn the engine off. Twice it dumped a lot of coolant so I sent it back to the garage. They coudnt replicate the issue found no code issues,did a pressure test on engine and expansion cap also a combustion leak tester without issue. Its not overheating according to the gauge but I do t hear the cooling fan kick in. Anyone had a similar issue or any ideas as to what could be causing this leak from the expansion tank?