[2.0.21] Cannot place ghost train on ghost rail

[sben]

What did you do?
Place rails ghosts. Try to place cargo wagon ghosts over them.

What happened?
Error: "Train ghosts must be built on rails"

What did you expect to happen instead? It might be obvious to you, but do it anyway!
Placing cargo wagon ghosts.

Does it happen always, once, or sometimes?
Always

Note: this is not a duplicate.
All error reports about this are from 2020 or older and marked as fixed. This is an issue again.

[Theragus]

can confirm this behavior, although I would strongly guess this is just a limitation of the ghost trains and ghost rail system in general, as a workaround placing rails and trains in the same blueprint does work, however.