hangs at Loading workspace. in ubuntu docker container

I am running `dotnet format` as part of an azure devops yaml pipeline, on a self hosted build agent, which is running as an ubuntu docker container.

Here is the yaml task:

```
- task: DotNetCoreCLI@2
condition: ne(variables['Build.Reason'], 'PullRequest')
continueOnError: true
displayName: 'dotnet format'
inputs:
command: 'custom'
custom: 'format'
workingDirectory: '$(Build.SourcesDirectory)/src'
arguments: '--verbosity diagnostic --verify-no-changes'

```

Here is the AzDO task output - it just hangs at "loading workspace.":

```
Starting: dotnet format
==============================================================================
Task : .NET Core
Description : Build, test, package, or publish a dotnet application, or run a custom dotnet command
Version : 2.221.0
Author : Microsoft Corporation
Help : https://docs.microsoft.com/azure/devops/pipelines/tasks/build/dotnet-core-cli
==============================================================================
Info: .NET Core SDK/runtime 2.2 and 3.0 are now End of Life(EOL) and have been removed from all hosted agents. If you're using these SDK/runtimes on hosted agents, kindly upgrade to newer versions which are not EOL, or else use UseDotNet task to install the required version.
/usr/bin/dotnet format --verbosity diagnostic --verify-no-changes
The dotnet runtime version is '6.0.19'.
The dotnet CLI version is '6.0.411'.
Using MSBuild.exe located in '/usr/share/dotnet/sdk/6.0.411/'.
Formatting code files in workspace '/azp/_work/1/s/src/foo.sln'.
Loading workspace.
```

This task eventually times out

The same pipeline running in a non dockerised setup is working, can see minor difference in version of cli and runtime version used in working environment - here is an example of successful output from same pipeline in this other env:

```
Starting: dotnet format
==============================================================================
Task : .NET Core
Description : Build, test, package, or publish a dotnet application, or run a custom dotnet command
Version : 2.221.0
Author : Microsoft Corporation
Help : https://docs.microsoft.com/azure/devops/pipelines/tasks/build/dotnet-core-cli
==============================================================================
Info: .NET Core SDK/runtime 2.2 and 3.0 are now End of Life(EOL) and have been removed from all hosted agents. If you're using these SDK/runtimes on hosted agents, kindly upgrade to newer versions which are not EOL, or else use UseDotNet task to install the required version.
/usr/bin/dotnet format --verbosity diagnostic --verify-no-changes
The dotnet runtime version is '6.0.16'.
The dotnet CLI version is '6.0.408'.
Using MSBuild.exe located in '/usr/share/dotnet/sdk/6.0.408/'.
Formatting code files in workspace '/home/foo/agent/_work/2/s/src/foo.sln'.
Loading workspace.
Determining projects to restore...
// shortened for brevity this goes on to succeed

```

Likewise if I establish an interactive terminal inside of the problematic container, `cd` into the directory `/azp/_work/1/s/src/` and run `dotnet format .` I get the same hang