What is needed to get LOG_DBG messages to show up? 

I see the LOG_WRN, and other levels working fine.  In the example code in samples/subsys/logging/logger/main.c, the severity_levels_showcase() function does not output the "Debug message example." message (but does output the Error.., Warning..., and Info... messages).   The "external logging system showcase" does output the debug level message, but I'm trying to get it to work just with the regular functionality, not the "external" stuff.

I see that prior to the call to severity_levels_showcase(), the log_demo_thread() invokes log_filter_set with a CONFIG_LOG_DEFAULT_LEVEL, so I thought perhaps the default level excluded DBG messages, but even after I changed the log_filter_set() to use LOG_LEVEL_DBG, the LOG_DBG messages are still not output.  For instance, in log_demo_thread() I tried:

log_filter_set(NULL, CONFIG_LOG_DOMAIN_ID,
                      log_source_id_get(sample_module_name_get()),
                      LOG_LEVEL_DBG);

I tried setting CONFIG_LOG_OVERRIDE_LEVEL=4, and saw no improvement.  I tried setting CONFIG_DEBUG=y, again it did not help.

I'm running the sample code as suggested:
west build -p auto -b qemu_x86 samples/subsys/logging/logger
west build -t run

I have Zephyr OS build v3.0.0-rc3-28-g6669629d0b00

thanks,
Lyn