ETC1 split alpha channel not compatible with the new Sprite Atlas

Because the quality of picture using with ETC2 format for high-frequency gradient picture is very bad，I try to use ETC1 Split Alpha Channel mode.It seems that ETC1 Split Alpha Channel mode is only compatible with the legacy Sprite Packer.Is that so?

 

Thank you.I found my previous statement is inaccurate.SpriteAtlas support ETC with Split Alpha Channel enable,but does support ETC Crunched with Split Alpha Chanel enable.

 

We have the similar problem. We are also using a Sprite Atlas with ETC compression and split alpha. It is working fine in the editor but all sprites turn pink on the device.
I suspect that the 'UI-Default.shader' shader is used on the device instead of 'UI-DefaultETC1.shader'. So I created a custom material which is based on the 'UI-DefaultETC1.shader' and used that on one of our Image components.
Now the image looks just fine.

I want to make clear that this is not a solution for this issue. To my understanding the correct material should be set automatically. So this is only a workaround. It would be really difficult, in our current game, to specify the custom material on every Image component that we are using.

Note that our atlases are packed together using addressables. Not sure if this is somehow related to the problem.