Two camera issue

My game uses two cameras.The game is a wechat mini game. One is for UI and the second is for the game map. The reason I had to use two cameras is because of pan and zoom.
The map is more than ten times bigger than the screen.
The main problem is that when user fastly clicked many times on the map, sometimes the second camera(that shows map) shows nothing but black screen while UI camera is working well.
I made two group, one is default and one is gamelayer.
This error only shows in some Android phones.
I tried several things but nothing’s worked.
Pls help me with this.
Thanks.

can you upload a zip of your project (perhaps just a minimal version with the issue)?

Sorry but I can’t. The client doesn’t allow.