I recently configured ESP-Prog and had it working well, but now serial output from the app is not showing (it was originally). I get output from the break points showing in the Output window, but no longer anything generated from the app by print/println. 

The USB driver setup looked OK, but I reinstalled and rebooted just to test. No change. 

Screen shot of debug session:

The USB cable is connected via the USB prog. 

No serial output if Serial Monitor open.

If I turn Verbose on the Uploader then I get the following output.

ESP32FSUpload.exe
## recipe.wwwfiles.upload.pattern
"c:\program files\microsoft visual studio\2022\community\common7\ide\extensions\k0rd3sfw.d3n/ESP32FSUpload.exe" -serial.port=COM13 p32\Debug" -target_platform="esp32" p32\tools\mkspiffs\0.2.3" -board.name="ESP32 Dev Module" -upload.verbose=True -upload.resetmethod={upload.resetmethod} -upload.speed=921600 sp32\2.0.5" -project.name="PlumbingTestRig.ino" -project.path="D:\Users\admin\Documents\Arduino\sketchbook\PlumbingTestRig" -tools.esptool.cmd="{tools.esptool.cmd}" -tools.esptool.cmd.windows="{tools.esptool.cmd.windows}" -runtime.tools.esptool.path="{runtime.tools.esptool.path}" sa-esp32-elf-gcc\gcc8_4_0-esp-2021r2-patch3/bin/" -build.spiffs_start="{build.spiffs_start}" -build.spiffs_end="{build.spiffs_end}" -build.spiffs_pagesize="{build.spiffs_pagesize}" -build.spiffs_blocksize="{build.spiffs_blocksize}" -build.partitions="min_spiffs" -network.password={network.password} -network.auth_upload={network.auth_upload} -network.port=3232 -upload.tool=esptool_py -tools.esptool_py.cmd="esptool.exe" -tools.esptool_py.cmd.windows="{tools.esptool_py.cmd.windows}" esp32\tools\esptool_py\4.2.1" -build.flash_mode=dio -build.flash_freq=80m
D:\Users\admin\Documents\Arduino\sketchbook\PlumbingTestRig\data\config.json
SPIFFS Creating Image...
[SPIFFS] data   : D:\Users\admin\Documents\Arduino\sketchbook\PlumbingTestRig\data
[SPIFFS] offset : 0
[SPIFFS] size   : 192
[SPIFFS] page   : 256
[SPIFFS] block  : 4096
iffs.exe" -c "D:\Users\admin\Documents\Arduino\sketchbook\PlumbingTestRig\data" -p 256 -b 4096 -s 196608 87bf4fb74ea94ad1dd062bdff52257/PlumbingTestRig.ino.spiffs.bin"
/config.json
SPIFFS Uploading Image...
[SPIFFS] upload : 7bf4fb74ea94ad1dd062bdff52257/PlumbingTestRig.ino.spiffs.bin
[SPIFFS] address: 3997696
[SPIFFS] port   : COM13
[SPIFFS] speed  : 921600
[SPIFFS] mode   : dio
[SPIFFS] freq   : 80m
ptool.exe" --chip esp32 --baud 921600 --port COM13 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size detect 3997696 87bf4fb74ea94ad1dd062bdff52257/PlumbingTestRig.ino.spiffs.bin"
esptool.py v4.2.1
Serial port COM13
Connecting......................................
A fatal error occurred: Failed to connect to ESP32: No serial data received.
For troubleshooting steps visit: https://docs.espressif.com/projects/esptool/en/latest/troubleshooting.html
SPIFFS Upload failed!

Thanks for confirming, the wiring diagram is available below:
https://www.visualmicro.com/pics/Debug-Help-ESP32-PROG-ALL-Connections.png

Related question: the ESP-WROOM-32 dev board I am using does not expose GPIO00 so I cant wire that pin. So far it seems to work fine without it. Is there functionality that will be effected by not having it connected?

Thanks. 

Alternatively pressing the "BOOT" button works.