Recently I started to have some weird artifacts on my prints, specially on bigger ones... I don't remember to have changed nothing that can cause it except to reduce the perimeters printing speed... somewhere during the printer, it starts to incorrectly retract on corners and it produce underextrussion artifacts... nothing related to linear pressure advance (I tested it both enabled/disabled, the artifacts always appears)... with the same gcode, it always prints the exact pattern... if you change something on the model or slicing parameters, it changes where it appear or even doesn't appear... but without any identifiable pattern... if I increase the perimeter speed or general % speed on the printer, it seems to push the changing layer further...
I tested a lot of things, including new hardware, different filaments, uploading the last version of marlin, etc. without any change on the results...
I tested a lot of things, what I see more relevant:
- Repated.jpg: three layers of gcode manually repeated over and over just changing Z, to be sure that it always prints the same... at certain height, it starts to retract on all corners causing underextrussion (I can hear how it retracts each time).
- Single: the smaller model I can print where the problem appears: I checked layers at 2/3 and top one and they're the same!
- SingleTop: the same gcode file, manually cropped to only print the top 6mm... no artifacts where it appear if you print the whole file...
- Staked1/2: the same gcode file, manually repeated and stacked over... the artifacts continues on the same gcode layers that prints normal on the lower copy...

Anybody have a glimpse on what's happening here???
Thanks!