Hi, I was skinning 4 parts at the same time. So all the process is identical and epoxy mixture is the same 
Everything was done at 21C. Epoxy is new. Bough in May.

1. Basecoat. Wail till B-stage.
2. Lay carbon fibre and bag at 20-30% vacuum ovenight. Removed vacuum bag and stored till the evening.
3. 3 coats of XCR clear. Wait 24 hours, cure in an oven for 8 hours at 60C
4. Sand, clean, dry. Then parts were left for 9 days to tue lack of time
5. 2 more coats of XCR clear. Waited 18 hours.
6. Post cure in an oven for 8 hours at 60C
7. Removed parts this morning from the oven.

But didn't check them. And when I came back in the evening I saw that epoxy sank on two pieces and shrank so that the edges lifted from the plastic piece.
I can see and feel ridges where the epoxy sank. But it was smooth after step 4. What's strange that other two pieces came out perfect. No epoxy sinking and no shrinking. All 4 pieces were made at the exactly same time. So epoxy mixture was always the same. Can it be some temperature issue? Not even heat distribution? I'm using powder curing oven. Test pieces were at
62C when measured still inside the oven


Parts are ABS. Would you suggest glueing laminate back to the part? What glue to use? Edges will be hidden at least 5 to 8 mm by other trim pieces.

ABS is virtually impossible to bond to, and also have quite a high CTE. When you put them in the oven, the parts are expanding with the heat. Carbon has a very low CTE, so the difference between the two materials, coupled with the fact the epoxy has a very poor bond with the ABS, results in the carbon delaminating from the plastic.

ABS requires very thorough keying prior to applying the base resin, ideally with 40 or 60 grit sandpaper and even scoring it with a blade. Even then, it's not likely to stay in place if it is subject to thermal cycling, those differences in CTE just cause too much stress.