When using a border or a drop shadow on a transparent layer, ther border or drop shadow will not appear. From my point of view, this behavior is a bug.
There exists a hack, to work around this bug:
Shadow for a transparent rect - Ask the community - Figma Community Forum
But that cannot be the solution. The background will be appear in the inspect mode and will confuse our developers.
Please give me a practicable advise how to handle this. My suggestion - fix it 