Opacity lost in epub preview

[こな5CC4]

I'm making this e-book on InDesign 2020.
The image is in Chinese but the items numbered ①~⑤ are set as buttons and are suppose to be 50% opacity until the mouse cursor hovers above it, so ②~⑤ were suppose to be 50% opacity while ① is 100%. But in preview, all of them show as 100%, same when exported.
Have tried changing the object style export options to rasterize container/ format png, but has no effect. Can someone help me with this, please?

 

[Derek Cross]

eBook is a generic term for digital books; which format are you wanting to use?

[こな5CC4]

Epub

[rayek.elfin]

I see your are using the epub preview, so you are creating an epub file.

Did you group the circle and number, and then changed the object export option to this?

Simple opacity will work, but remember that blend effects are only rasterized correctly when all affected objects are grouped and rasterized.

[rayek.elfin]

Btw, it works for me if I create this group before turning it into a button.

[こな5CC4]

Oh, the circled numbers were added on with the photo editor after I took the photo on my phone, so they are not on the Indesign file. I thought it'll make it easier to explain which item I'm talking about. But sorry if it made it confusing.