iot: dotnet publish / run for linux-arm fails with NetCore5 targets in preview 5+

Describe the bug

Running dotnet publish for a project with target netcore5 fails with the current runtime

Global.json at the time of this writting:

{
  "tools": {
    "dotnet": "5.0.100-preview.5.20251.2",
    "runtimes": {
      "dotnet/x64": [
        "2.1.11"
      ]
    }
  },
  "sdk": {
    "version": "5.0.100-preview.5.20251.2"
  },
  "msbuild-sdks": {
    "Microsoft.DotNet.Arcade.Sdk": "5.0.0-beta.20261.9",
    "Microsoft.DotNet.Helix.Sdk": "5.0.0-beta.20261.9"
  }
}

Steps to reproduce

On the desktop (Windows) run:

cd projects\iot
build
# passes as expected
cd src\devices\Ads1115\samples
dotnet publish Ads1115.Samples.csproj -r linux-arm -c debug --self-contained false
# passes as well - all fine (the path \src\devices\Ads1115\samples\bin\Debug\netcoreapp2.1\linux-arm\publish now contains binaries ready to run on the pi)

# now change in Ads1115.Samples.csproj the <TargetFramework> entry to <TargetFramework>netcoreapp5.0</TargetFramework>
dotnet publish Ads1115.Samples.csproj -r linux-arm -c debug --self-contained false

An error is now reported:

C:\projects\iot2\src\devices\Ads1115\samples>dotnet publish Ads1115.Samples.csproj -r linux-arm -c debug --self-contained false
Microsoft (R)-Build-Engine, Version 16.7.0-preview-20229-03+2cee6d020 für .NET
Copyright (C) Microsoft Corporation. Alle Rechte vorbehalten.

  Wiederherzustellende Projekte werden ermittelt...
C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj : error NU1102: Das Paket "Microsoft.NETCore.App.Host.linux-arm" der Version (= 5.0.0-preview.5.20230.9) wurde nicht gefunden.
C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj : error NU1102:   - 2034 Version(en) gefunden in "https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json" [ Nächste Version: 5.0.0-preview.5.20224.13 ]
C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj : error NU1102:   - 22 Version(en) gefunden in "nuget.org" [ Nächste Version: 5.0.0-preview.4.20251.6 ]
C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj : error NU1102:   - 0 Version(en) gefunden in https://dotnet.myget.org/F/dotnet-core/api/v3/index.json.
C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj : error NU1102:   - 0 Version(en) gefunden in https://dotnetfeed.blob.core.windows.net/dotnet-iot/index.json.
C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj : error NU1102:   - 0 Version(en) gefunden in https://dotnetfeed.blob.core.windows.net/dotnet-tools-internal/index.json.
  Fehler beim Wiederherstellen von "C:\projects\iot2\src\devices\Ads1115\samples\Ads1115.Samples.csproj" (in "1.11 sec").
  2 von 3 Projekten sind für die Wiederherstellung auf dem neuesten Stand.

Expected behavior

Build passes

Actual behavior

See above. It looks a bit as if the SDK build that’s currently referenced is incomplete. The problem does not happen if going back to the “official” beta version 5.0.100-preview.4.20258.7

Versions used SDK: 5.0.100-preview.5.20251.2 [C:\Program Files\dotnet\sdk] Runtime: Microsoft.NETCore.App 5.0.0-preview.5.20230.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]

Edit See below: The problem got even worse with previews 6 and 7. I can’t get them to work at all on the Raspi when targetting NetCore 5.0.