The fix for this issue is available in the latest InDesign update 15.1
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Adobe InDesign team
An error occurred while saving the commentJieru Xu commented
(1) "-edit-->preferences-->appearance to black-->changed output to print all black accurately"
This didn't work.
(2) "placed a black image over background instead of filling the background with the 'rich black swatch'"
This didn't work, either.
(3) emerged a new transparent layer and the original image in Photoshop, and then dragged to InDesign
Didn;t work either.
I think I'm totally crazy.