I've completed everything 100% but the Perfection achievement doesn't appear.

[Kamuro]

If I had known, I should spend my time with another games. Sorry man I just feel worthless. I don't think everything I've done over the holidays will be a waste. This year is suck...

[EleventhStar]

did you go to the summit? (at train tracks if memory serves)

[Buffmania]

Did you go to the summit north of the railroad? There's a cutscene there that triggers the achievement.

[OdinDerHarte]

That happened to me in other games too where i spend like +30h only for one achievement that i then didn't got for some reasons. Thats why i stop the achievement hunting and just start to enjoy the games.

[red255]

haven't earned Stardew achieves in a while but yeah sometimes they didn't pop in steam even though they popped in steam, restarting the day usually fixed it.

Thought they fixed it, but hard to test cuz I already got the ones i was going to get. (not the prarie king ones because that game is horrid.)

[NBOX21]

The very next day after getting 100% completion, the boulder blocking the path to the path from the train station will be removed, allowing you to reach the summit. The Perfection achievement should unlock once you reach the summit and view the final cutscene.

[Kamuro]

I finally got the achievement. It was quite embarrassing for me to get discouraged for a moment. I'm so unmanly lol. And thanks for the answers and questions that made me patiently come back and download and try again. It worked. I think I should reconsider whether I should continue to be an Achievment Hunter. Anyway, thanks to everyone who replied to this comment. You guys made my New Year's Eve more lively and meaningful.