What would be the correct format string to parse the following date:

2021-07-30T13:28:30.942654-04:00

The wizard generates the following string:

yyyy-MM-ddT%H:mm:ss.ffffffzzzz

However, when I view the result in the log viewer, there's no time zone column, and the time is displayed like:

1:28:30 PM.942

If you want to display the timestamp, try adding zzzz to the time display format settings.  You will also find settings on how timezones should be handled with regard to the display time.  It may be worth modifying these to see if you can get the expected result.

Regarding the final screenshot, I would suggest that either the timezone is not being parsed (zzzz) or it is being parsed into the current time zone making the conversion redundant.  If you think there may be a bug here, please send a sample log file along with recreation steps.