photos app crash in ios 11 using saving to files

I encounter this situation on 2 different phones - iphone x and iphone 7 plus.

Both on ios 11.

I use Camera Roll - Save to Files feature to transfer photo to icloud drive ( where I created various folders). After every 20-40 photos/videos, Photos app will crash and hang and show a blank screen.

I had to exit Photos app and relaunch it. But it will keep recurring again after some photos/videos file transfer.

At one point, when I rebooted the phone, the entire camera roll was empty and I saw a message "Restoring.." in camera roll where some kind of self restore was triggered.

Just wondering if anyone encountered similar situation and how to resolve this.

Apple support was not very helpful on this as this occured in 2 different phones.