Welcome to EVE!
This is a fairly common issue. Please bug report it, then try logging out and back in to see if it will reset the status to ‘completed’ (the game checks your skill statuses whenever you log in).
You can also try training another shorter skill to see if the skill-status-check that triggers upon skill completion will update the tutorial mission.
If that doesn’t fix it, a support ticket to the GMs is the last ditch effort to see if they will manually flag that step as complete to move you onward - this can take a few days to be completed, but they tend to be fairy quick. Just depends on how many tickets are coming in, and around a new release (12/8 was a major patch) it can be a bit busier.
Good luck, and let us know what fix works for you so we have it handy for the next person!