Cracks on coving joins

[MattFinish]

I put up duropolymer coving last summer, used plenty of non solvent adhesive also in between the joins. Before painting, I put 2 coats easi fill over the joins and feathered out, sanding in between, then emulsioned over.

Soon after I noticed cracks in all places where the joints are.

How do I resolve this? I'm guessing flexible decorators caulk this time (twice as it shrinks) as a powder filler failed the first time, then prime with Zinsser BIN then emulsion over again?

 

[stevethespreader]

Best practice is to leave a tiny gap on joints of a couple of a mm or 2 when installing instead of butting up to each other this enables the filler to hide the joint by infilling