Block Editor: Cover block overlay opacity not working when it has no media

Expected behavior

For a Cover block without any media (no image, nor video) when overlay opacity is set to any number below 100% it correctly displays the color + opacity in the Android app editor.

Actual behavior

The overlay opacity is only correctly displayed IF the Cover block has media, otherwise two things happen:

1. the Android editor does NOT show the overlay opacity setting in the Block settings
2. the Android editor does NOT render the overlay opacity correctly, showing a block with 100% opacity with the solid overlay color

Screenshots of the behavior

The screenshots below were all taken with the Cover Block in the same state, with overlay opacity = 10%.

Web Editor	Web Preview	App Editor (bug)	App Preview

Steps to reproduce the behavior

I was able to find a couple of ways to reproduce it:

First Way - All inside WordPress Android App

0. Open WordPress Android app and Log In to your account
1. Choose a page / create a new page
2. Add the Cover block to it
3. Set any media for the cover block
4. Set a text inside the Cover block (just for better visibility on the bug)
5. Set the paragraph block text color
6. Open Cover block options
7. Check that you have the option of setting an overlay opacity
8. Set an overlay color to the same color as the paragraph text color set on step 5
9. Set overlay opacity to something low, like 10%
10. Check that editor looks as expected: background media, with an overlay, with a text on top of it
11. Tap to see the preview
12. Check that preview looks as expected: background media, with an overlay, with a text on top of it
13. Open Cover block options
14. Tap on "Clear Media" to remove the media
15. Check that editor DOES NOT look as expected: solid overlay color with no transparency, text with same color (impossible to see)
16. Open Cover block options
17. Check that "Overlay Opacity" option is not there anymore
18. Tap to see the preview
19. Check that preview LOOKS as expected: overlay color WITH previously set transparency, text with same color (but possible to see, thanks to overlay opacity)

Second Way - WordPress Web Editor (on mobile or computer) + Android app

0. Open WordPress Web on your device browser and the Android app as well, and Log In to your account in both places
1. Web Editor: Choose a page / create a new page
2. Web Editor: Add a Cover block to it
3. Web Editor: Choose a color for the cover block (don't add any media)
4. Web Editor: Set a text inside the Cover block (just for better visibility on the bug)
5. Web Editor: Set the paragraph block text color
6. Web Editor: Open Cover block options
7. Web Editor: Check that you have the option of setting an overlay opacity
8. Web Editor: Set overlay color to the same color as the paragraph text color set on step 5
9. Web Editor: Set overlay opacity to something low, like 10%
10. Web Editor: Check that editor looks as expected: background media, with an overlay, with a text on top of it
11. Web Editor: Tap to see the preview
12. Web Editor: Check that preview looks as expected: background media, with an overlay, with a text on top of it
13. Web Editor: Hit "Update" to save the changes
14. App Editor: Refresh the Pages list
15. App Editor: Select the same page you edited using the Web Editor
16. App Editor: Check that editor DOES NOT look as expected: solid overlay color with no transparency, text with same color (impossible to see)
17. App Editor: Open Cover block options
18. App Editor: Check that "Overlay Opacity" option is not there
19. App Editor: Tap to see the preview
20. App Editor: Check that preview LOOKS as expected: overlay color WITH previously set transparency, text with same color (but possible to see, thanks to overlay opacity)

Tested on Samsung S21+, Android 12, WPAndroid 21.0-rc-1

Reproduce the issue in the WordPress Android app using a Cover block without media, then compare the editor with the preview after setting a low overlay opacity. The fix is done when the Overlay Opacity setting remains available and the editor renders the saved opacity correctly with and without media.