Unable to debug with Portable PDB

I need to debug my .net application (simple hello world console app) using Mono on linux. When I convert the windows PDB to portable PDB, deploy the portable PDB to the linux environment, and try to debug it mono debug extension of VS Code, it doesn't work.
However, if I compile the executable using embedded PDB, and then use the pdb2pdb tool to extract the PDB and convert it to Portable PDB, deploy this portable PDB to the linux environment, then I am able to debug the code.
I am also able to debug the code by using the portable PDB generated by Visual Studio 2017 itself. the portable PDB and PDB2PDB tool is exactly same size, If I use PDB2XML I get the same output, however, I do notice changes in binary comparison between the files.