Sorry for the delayed response.
If you go to this project, and use the vMicro > Add Code > Add Custom GDB Debugger button, this will add two files to the project.
If you then open the SAMD_ZERO.Debug.debugger_launch.json file, and paste in the JSON from your logs (Its below, but can also be obtained by running Debug > Attach to Process, and scrolling to the end of the Output Window). The only edit I have made is to remove the "reset halt" from the end of the debugServerArgs command:
{
"serverLaunchTimeout": 5000,
"filterStdout": false,
"filterStderr": true,
"targetArchitecture": "arm",
"stopAtEntry": false,
"externalConsole": false,
"MIMode": "gdb",
"MIDebuggerServerAddress": "localhost:3333",
"cwd": afruit_feather_m0\\Debug",
"MIDebuggerPath": ne-eabi-gcc\\9-2019q4/bin\\arm-none-eabi-gdb.exe",
"MIDebuggerArgs": "",
"debugServerPath": "C:\\ProgramData\\vmicro\\tools\\openocd-0.10.0.20200213\\bin/openocd.exe",
"debugServerArgs": "-d2 -l adafruit_feather_m0\\Debug/bleuart_cmdmode.ino_DebugOpenOCD.log}\" -s \"C:\\ProgramData\\vmicro\\tools\\openocd-0.10.0.20200213/scripts/\" -f \"interface/jlink.cfg\" -c \"transport select swd\" -f md\\1.7.8/variants/feather_m0/openocd_scripts/feather_m0.cfg\" -c \"init\"",
"setupCommands": [],
"program": eather_m0/Debug/bleuart_cmdmode.ino.elf",
"logging": {
"moduleLoad": false,
"trace": false,
"engineLogging": false,
"programOutput": false,
"exceptions": false,
"traceResponse": false
},
"visualizerFile": afruit_feather_m0\\Debug\\debugger_tmp.natvis",
"showDisplayString": true
}
Then change the Debugger selection from "Segger Jlink (SWD)" and change it to Manual/Custom.
Hopefully it won't reset in the core init() code, and will start the debugging session fully next time you try the Debug > Attach to Process option.
If there is still an issue with Debug > Start Debugging, there could be a timing issue at play as well.