Failed to read flash WR3L module

[jackrosenthal]

I have a couple of WR3L modules. I've tried reading the flash from them using ltchiptool , but get a funny error once the chip is in download mode:

[ENV: ltchiptool-venv] jrosenth ~ % ltchiptool --verbose flash read ambz ~/bak-009s.bin
D: Found PlatformIO Package (v1.0.2) - /home/jrosenth/.platformio/platforms/libretiny
D: Found Local data snapshot (v1.1.0) - /home/jrosenth/ltchiptool-venv/lib/python3.10/site-packages/ltchiptool
I: Available COM ports:
I: |-- ttyUSB0 - FT232R USB UART - FT232R USB UART - FTDI (0403/6001)
I: |   |-- Selecting this port. To override, use -d/--device
I: |-- ttyS4 - n/a
I: Connecting to 'Realtek AmebaZ' on /dev/ttyUSB0 @ 1500000
D: Linking: stage 0
D: Linking: stage 1
D: Linking: stage 2
D: Linking: stage 3
I: Connect UART2 of the Realtek chip to the USB-TTL adapter:
I: 
I:     --------+        +-------------------------------
I:          PC |        | RTL8710B                      
I:     --------+        +-------------------------------
I:          RX | ------ | TX2 (Log_TX / PA30)           
I:          TX | ------ | RX2 (Log_RX / PA29)           
I:         RTS | ------ | CEN (or RST, optional)        
I:         DTR | ------ | TX2 (Log_TX / PA30, optional) 
I:             |        |                               
I:         GND | ------ | GND                           
I:     --------+        +-------------------------------
I:  
I: Make sure to use a good 3.3V power supply, otherwise the adapter might
I: lose power during chip reset. Usually, the adapter's power regulator
I: is not enough and an external power supply is needed (like AMS1117).
I:  
I: If you didn't connect RTS and DTR, you need to put the chip in download
I: mode manually. This is done by connecting CEN to GND, while holding TX2 (Log_TX)
I: to GND as well. After doing that, you need to disconnect TX2 from GND.
I:  
I: If the download mode is enabled, you'll see a few garbage characters
I: printed to the serial console every second.
I: |-- Success! Chip info: Realtek RTL87xxB
I: Reading 2 MiB @ 0x0 to '/home/jrosenth/bak-009s.bin'
  [----------------------------------------------------------------]    0%
E: ValueError: Failed to read from 0x0
E: |-- File "/home/jrosenth/ltchiptool-venv/lib/python3.10/site-packages/ltchiptool/soc/ambz/flash.py", line 132, in flash_read_raw

This is using an external 3.3V supply. For adapters, I've tried an FTDI 2142C, and a FTDI 2242C. Any advice?

I'm using GPIO_A29 and GPIO_A30 for the UART.