Underextrusion when there is a drastic section change

[Thunder35]

Hi there. I have a cr-10S since more than a month ago, after two 1kg spools gone I am still here with the same problem. With items that have a drastic section variation I always have an underextrusion on that layer.
I changed hotend to a V6, changed nozzle, updated the firmware, tried various slicers, but it is still there. I don't know what happens on the max section layers, but something is hidden behind it.
Sometimes they are less evident like in the photo, sometimes it is so hard the top and bottom pieces will just fall apart with a minimal force. It can also happen if there is an internal hole.
In the photo below the underextruded layer is the one where there is the left tip.
underextrusion.jpg

Thank you.

[airscapes]

is it always the same layer?? Maybe you have a problem with the z axis not moving the proper distance.

[Thunder35]

is it always the same layer?? Maybe you have a problem with the z axis not moving the proper distance.

No, it is not at the same height, it just happens if the next layer section is too much bigger or smaller.
This is a new piece I printed today, the layer is missing where the next layer will have a way smaller section.
underextrusion2.jpg underextrusion3.jpg

It really doesn't have any sense..