Why is my print going so horribly wrong after the 5th layer?

Hi all, can somebody maybe try to give me an idea of why this is happening to my prints after they start off so well?

I?m printing a box on my CR-10 using Cura with Amazon PETG at 0.4mm layer height and 220c/80c temps. The layers stick great to the bed and look perfect until after the triangles finish on the 5th layer. After this the layers curl up really bad as you can see in this pic.

Is there a setting on Cura which I should be changing or modifying? Any suggestions on what i can do here will be greatly appreciated?
Thank u!

0.4mm layer height is pushing it with a stock 0.4mm nozzle. switch to 0.32 for starters.
It looks like there is most likely a design or slicing flaw.
That layer clearly isn't being printed close enough to the preceeding layer, so it's simply not sticking.

Check the design file.

Hi, i'm not sure what you mean by check the design file because it was just a simple cube created in tinkercad and sliced in Cura. I will however continue to print using 0.2 instead of 0.4a. Thanks

are you using a raft ?

I actually just used a skirt but the base of the cube printed and stuck perfectly to the bed. It was only after the triangles that I guess you could call the cover layer for those triangles started to curl up.

weird, the triangles look like infill.
But why would you have a single layer of infill and then a solid layer - on a cube.

Yeah I also find it odd that cura sliced it that way. Here's a video of the process in Cura and as you can see it's actually on layer 7 that it creates that problematic layer.

https://youtu.be/curUYixQw7s

have you tried to print anything else ?

That slicing is just bizarre.

Yes i've printed other shapes at 0.2mm and they printed fine. What slicer do you recommend so that I can try to print that same box again sliced by another app?

well just been looking into this on another thread.
for the free stuff - it looks like a pronterface & slic3r combo is probably the best control & print option around.
I - personally - recommend simplify3d. No it's not free, but it is extremely good and I don't regret buying it :-)

That said there are a bunch of free internet based slicers around. My internet is dicey at best (i'm almost the last house on the local telephone exchange) and my wifi in my workshop is also a tad dodgy, so I don't do cloud/internet based software.
Plus I simply don't like the idea of it anyway :-)

Here's a list of some of the ones I either haven't tried - or might have tried a few years ago when they didn't really work and I hadn't bought simplify3d :-)
https://all3dp.com/1/best-3d-slicer-...re-3d-printer/