I seem to be having the same issue. First it only happened in the first few layers like in the pictures. Usually in the same spot but not always. I was generally able to just restart the print and have it work fine. However, I just lost one halfway through. The printer just stops, heater and fans are still running and the web interface thinks that the print is still running. It give me the option to pause but nothing happens. Very weird. I have included an m122 readout below. I will reduce the microstepping as you suggest. Just doing my part to help diagnose.
M122
=== Diagnostics ===
Used output buffers: 3 of 32 (9 max)
=== Platform ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 1.21 running on Duet WiFi 1.02 or later + DueX5
Board ID: 08DDM-9FAM2-LW4S8-6JTDG-3SD6R-13YMX
Static ram used: 16152
Dynamic ram used: 100536
Recycled dynamic ram: 2096
Stack ram used: 1224 current, 6632 maximum
Never used ram: 5656
Last reset 01:30:37 ago, cause: power up
Last software reset at 2018-04-29 01:54, reason: User, spinning module GCodes, available RAM 5656 bytes (slot 3)
Software reset code 0x0003 HFSR 0x00000000, CFSR 0x00000000, ICSR 0x04417000, BFAR 0xe000ed38, SP 0xffffffff
Error status: 0
Free file entries: 9
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest block write time: 126.7ms
MCU temperature: min 19.7, current 30.5, max 31.0
Supply voltage: min 23.7, current 23.8, max 24.3, under voltage events: 0, over voltage events: 0
Driver 0: standstill, SG min/max 0/393
Driver 1: standstill, SG min/max 0/1023
Driver 2: standstill, SG min/max 0/267
Driver 3: standstill, SG min/max 0/1023
Driver 4: standstill, SG min/max not available
Driver 5: standstill, SG min/max not available
Driver 6: standstill, SG min/max not available
Driver 7: standstill, SG min/max not available
Driver 8: standstill, SG min/max not available
Driver 9: standstill, SG min/max not available
Expansion motor(s) stall indication: no
Date/time: 2018-04-30 14:58:10
Slowest main loop (seconds): 0.980719; fastest: 0.000051
=== Move ===
MaxReps: 508091, StepErrors: 0, LaErrors: 0, FreeDm: 121, MinFreeDm 120, MaxWait: 3635039563ms, Underruns: 277, 0
Scheduled moves: 64659, completed moves: 64629
Bed compensation in use: mesh
Bed probe heights: 0.000 0.000 0.000 0.000 0.000
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
Heater 0 is on, I-accum = 0.0
Heater 1 is on, I-accum = 0.8
=== GCodes ===
Segments left: 1
Stack records: 2 allocated, 0 in use
Movement lock held by null
http is idle in state(s) 0
telnet is idle in state(s) 0
file is doing "G1 X135.148 Y112.675 E0.0579" in state(s) 0
serial is idle in state(s) 0
aux is idle in state(s) 0
daemon is idle in state(s) 0
queue is idle in state(s) 0
autopause is idle in state(s) 0
Code queue is empty.
=== Network ===
Responder states: HTTP(1) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
HTTP sessions: 1 of 8
- WiFi -
Network state is running
WiFi module is connected to access point
Failed messages: pending 0, notready 0, noresp 0
WiFi firmware version 1.21
WiFi MAC address 5c:cf:7f:a4:89:b8
WiFi Vcc 3.38, reset reason Turned on by main processor
WiFi flash size 4194304, free heap 15552
WiFi IP address 192.168.1.201
WiFi signal strength -64dBm, reconnections 0, sleep mode modem
Socket states: 2 0 0 0 0 0 0 0
=== Expansion ===
DueX I2C errors 0