Hi there [yun],
We can provide some guidance if you're not seeing your Hidden Album in the Photos app on your iPhone. To start, let's follow these steps to be sure it's turned on:
To turn off the Hidden album:
1. Go to Settings and tap Photos.
2. Scroll down and turn off Hidden Album.
3. On an iPhone or iPad, the Hidden album is on and visible by default. When you turn off the Hidden album, any photos or videos that you've hidden won't be visible in the Photos app.
After you've ensured Hidden Album is turned on in Settings > Photos, you can follow these steps to view in in the Photos app:
Find the Hidden album
1. Open the Photos app.
2. Tap the Albums tab.
3. Scroll down and look for the Hidden album under Utilities. On iPad, you might need to tap the sidebar icon in the upper-left corner first to see your albums.
The related article linked in blue at the top left corner of this page provides more information.
Take care.