There’s three different 142×12 mm standards, DT swiss do a ratchet qr that works perfectly on all of them, you just need to know the right one. Crc have them for around £25.
I had a quick Google and crc reviews say the x12 doesn’t fit, I think it’s the e-thru you need as if you google giant e-thru its a bit more positive. You’d think giant would be more helpful- there’s even a post on their fb asking which system it is and they’ve just replied the specs are 142×12….
http://www.chainreactioncycles.com/dt-swiss-rws-e-thru-alloy/rp-prod123930
My money would be on that, don’t blame me if it doesn’t fit though! You could probably buy one of each and send 2 back if you were careful with them.