@dc42 thank you!

@huskypsyd Firmware 3.3RC3

Same issue here. Worked fine in v3.2. 3.3 is causing me an issue now.
5/30/2021, 8:33:29 PM Warning: Auto tune of heater 1 failed due to bad curve fit (R=2.783, 1/C=0.0075:0.0074, D=4.9)
5/30/2021, 8:30:56 PM Auto tune starting phase 5, tuning with fan on
5/30/2021, 8:28:54 PM Auto tune starting phase 4, tuning with fan off
5/30/2021, 8:26:58 PM Auto tune starting phase 3, heating system settling
5/30/2021, 8:26:12 PM Auto tune starting phase 1, heater on
5/30/2021, 8:26:06 PM M303 T0 S205
Auto tuning heater 1 using target temperature 205.0°C and PWM 1.00 - do not leave printer unattended

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B3950 ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0 ; create bed heater output on out0 and map it to sensor 0
M307 H0 R0.447 C328.1 D1.77 V24.1 S1 B0 ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S150 ; set temperature limit for heater 0 to 150C
M308 S1 P"temp1" Y"thermistor" T100000 B4267 ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1 ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 R2.656 C131.0:130.9 D5.81 S1.00 V24.2 B0 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S300 ; set temperature limit for heater 1 to 300C

@dc42 I must have been looking at an older instructional page. I swapped out A for R and now it is working without issue.

@droftarts Thanks that was super helpful!

@droftarts Thanks for the response.
M115: FIRMWARE_NAME: RepRapFirmware for Duet 3 Mini 5+ FIRMWARE_VERSION: 3.2.2 ELECTRONICS: Duet 3 Mini5plus WiFi FIRMWARE_DATE: 2021-02-11

Can you say more about M501 and M307? I am coming from Marlin and have been having trouble with the transition.

I am using a mini5+ and ran a PID for both the hotend and the heated bed and keep getting an "Error: M307: bad model parameters." It seems to work fine, but not sure if I am doing something wrong. Any help would be greatly appreciated. Here are the configs:

; Heaters
M308 S0 P"temp0" Y"thermistor" T100000 B3950 ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0 ; create bed heater output on out0 and map it to sensor 0
M307 H0 A0.449 C313.7 D2.43 V24.1 S1 B0 ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S150 ; set temperature limit for heater 0 to 150C
M308 S1 P"temp1" Y"thermistor" T100000 B4267 ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1 ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 A2.536 C132.0 D6.10 V24.2 S1 B0 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S300 ; set temperature limit for heater 1 to 300C