Thanks, we have confirmed the issue and found the root cause. The latest nRF52 Arduino package changed the OpenOCD command template to a format that was not supported by VisualGDB:
tools.openocd.upload.pattern="{path}/{cmd}" -s "{path}/share/openocd/scripts/" -f "{runtime.platform.path}/variants/{build.variant}/{build.openocdscript}" -c "program {{{build.path}/{build.project_name}-merged.hex}} verify reset exit"
The extra {{}} after the ‘program’ argument intended to pass the literal ‘{‘ and ‘}’ to OpenOCD was not properly translated.
We have updated VisualGDB to handle this correctly. Please try this build: VisualGDB-5.6.108.4712.msi