Cannot open bonus hidden chest in Iben Fahd’s sanctum

Bug Report
1

In addition to a description of the bug you are reporting, please provide:

Device Type:ipad 9
Device Model:iPad 9
Device Operating System: iOS
Diablo Immortal App Version:current

2

I have the same problem.
Android

3

To clarify, do you mean you entered the sanctum and used 377 keys to open all the locked chests, and the final, extra chest did not come out from the ground?

Or do you mean the first chest (that’s free to open) in which case, is it this…