breakpoints not set if PDBs were built on windows

if I build my project in visual studio and copy my whole bin directory from windows to linux, then start debugging, no breakpoints are set when the debuggee launches.

in the output window, i see:

22: (5731282) ->=breakpoint-modified,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",warning="No symbols have been loaded for this document."}

however, if I do a clean 'dotnet build' on linux (with the same source files) then breakpoints are set correctly on launch.

here's my project.json:

{
	"name" : "GatewayClient",
	"version": "1.0.0-*",
	"buildOptions": {
        "emitEntryPoint": true,
        "debugType": "portable",
        "copyToOutput": "appsettings.json",
        "define": []
	},

	"dependencies": {
		"Microsoft.Extensions.Configuration": "1.1.0",
		"Microsoft.Extensions.Configuration.Json": "1.1.0",
		"Microsoft.NETCore.App": {
			"type": "platform",
			"version": "1.1.0"
		},
		"Newtonsoft.Json": "9.0.1"
	},

	"frameworks": {
		"netcoreapp1.0": {
			"imports": "dnxcore50"
		}
	}
}

Reproduce the issue using the project.json configuration by copying a Windows-built bin directory to Linux, then compare it with a Linux dotnet build. Start from the breakpoint-modified output showing that symbols were not loaded; done means breakpoints are set when the debuggee launches in both cases.