What I did last night (it was around 2 a.m.) is saved and exited the game.Did you actually open the game up and save after you synced your switch clock yesterday, or no? If you played in game on today’s date, saved and exited, and then changed your clock but didn’t play again until today (with the same date you played on yesterday), then the game didn’t really experience time travel. You would’ve had to actually play and save on yesterday’s updated date for the game to process today as a different day.
Then I went to my Switch's settings and turned back on date and time syncing.
Today, I booted the game sometime in the morning (probably 9 or 10) and didn't get the morning message or anything and everything has been the same as the previous day.
I'm not sure if it's also because the date would have already been the 20th by then since I did it early in the a.m.