Bug in PPro panel SDK regarding project private metadata

Hello,

I was working with the PPRo 2017 project private metadata and I found that we could not persist custom metadata (those that are not present by default).

I used the official documentation provided here: Samples/PProPanel at master · Adobe-CEP/Samples · GitHub (modify project metadata) and even if I click save the project, whenever I re-open it, the newly created metadata is lost.

Is it intended or known?

Thanks in advance