With the parts in the 12x142 adapter kit, it is possible to mount a Specialized Diverge with 12x135 in the rear using the M135 side of the spacer which came with the Kickr (so NOT the 12x142 spacer which came with the kit). All in all you only need three pieces which come with the kit: the cassette washer, the thru-axle bushing and the thru-axle end plug for the QR skewer. You do not need to use the QR which comes with the kit, the original QR works too (you can see how much of the conversion kit skewer sticks out through the bushing in one of the pictures below).

It's not a perfect conversion for the Diverge - the tapered bushing intended for DT Swiss style thru-axles has a slightly smaller diameter and depth than the Specialized thru-axle. This translates to the non-drive side not being fully clamped down and results in some wobble. I filled up with a leftover floor protector intended for furniture which covers the thru-axle hole entirely; this seats the bike rock solid. If you're handy with and have access to a shop you might be able to mill your own conversion kit quite easily considering how small and simple the parts are!

Also, the rear derailleur alignment is WAY off with the limit screws going beyond the smallest cog on the cassette compared to the wheels coming with the Diverge. If you intend to play Zwift and use the gears you will most likely want to adjust the limit screws before going at it.

Some pictures... do note that the white bushing is the floor protector I was talking about, it does NOT come with the conversion kit:

i.imgur.com/9ZT9SkI.jpg - the Diverge mounted on a Kickr in all its glory
i.imgur.com/Dh0nZJp.jpg - view of the M135 side of the Kickr bushing through the thru-axle hole
i.imgur.com/sqjG3NZ.jpg - view of the QR with the tapered bushing
i.imgur.com/PJeg6hC.jpg - floor protector on top, the three pieces necessary which came with the kit, the kit QR
i.imgur.com/z06L1ND.jpg - the parts on the QR in the order which they go on the Kickr

I apologize for the pictures not being URLs but I registered literally only to post this, since my research into the compatibility was fruitless... and this forum post was the first hit on Google.