No idea what the deal is here.
This is on my slightly modded Creality Ender 3 Pro. (It's got a CR-Touch, better springs, a metal extruder assembly, an upgraded official Ender 3 Pro motherboard with quieter stepper controller capability. Nothing all that invasive.) Identical gcode worked perfectly fine on my Ender 3 V2 Neo. (Which is sufficiently similar that gcode is interchangeable.) I've used that particular roll of filament for other prints before and had no issues. And the same printer has given me no other similar issues with other prints, including prints that were taller than where it failed on these photographed prints.
After the one on the right failed, I assumed it was a clog and did a cold pull. The second print (still on the bed) started out just fine, but started underextruding the same way at almost exactly the same place. I say "almost" because looking closely in person, it does look like the second started underextruding just maybe 3 to 4 layers later than the first.
I suppose it's possible it was a second clog at almost exactly the same place on the second print, but it's pretty coincidental if so. Plus recovering spontaneously on that second print is pretty weird.
I dunno. Just very weird and I'm hoping folks here have an idea what I might look into to find a solution. Thanks in advance!
Also, just a few more images in case it helps:
Update (finally): Thanks to all who commented. I printed it again with different filament and it printed fine. I'll probably give the offending filament a dry, but I probably don't have enough of it to try another print, so I may not get confirmation that was the (only) issue. Anyway, I'm happy it's not some painful configuration thing, though. Thanks again for the input!
I suspect the retraction settings and or the extruder gear clamping on the filament to be the main issue. I upgraded my ender 3 pro to direct drive for a similar issue. Essentially what happens is that the extrusion goes smoothly when printing long uninterrupted sections, but these under extrusions would appear near or after areas that required a lot of retractions. If your retraction distance is set too small (5-10 mm) the filament gripping gears on the extruder end up going back and forth a lot on the same section of filament in order to start and stop quickly. This wears down the filament itself and suddenly the gears don't have any traction on the filament to push it, and hence the under extrusion. This is fairly easy to diagnose however. You should check if there is a lot of filament dust around your extruder gears. That was the smoking gun in my instance. I fixed it by reducing the tension in the spring loaded arm and reducing the retraction speed while upping the retraction length to 15mm. I ran with those "fixes" for quite a while before upgrading to a direct drive. Hope this helps.