No definition found for referenced assemblies

[chickenSandwich]

Issue Description

After updating to 1.21.4, Go to Definition for referenced assembly types does not work

Steps to reproduce

Update to 1.21.4
List test = new List();
Press F12 (Or choose Go to Definition from context menu)

Expected behavior

Open the [metadata] csharp file and go to the definition

Actual behavior

No definition found for 'List'## Logs ##

Work-around (Verification that 1.21.4 is the culprit)

Go to the Extensions pane
Choose Install Another Version from the C# extension
Choose 1.21.3
Restart VSCode
Repeat the ## Steps to reproduce

Note:

Upon restarting VSCode after updating to C# 1.21.4 the Output window is blank
Upon restarting VSCode after Install Another Version to C# 1.21.3
The Output window reports:

Installing C# dependencies...
Platform: linux, x86_64, name=ubuntu, version=18.04

Downloading package 'OmniSharp for Linux (x64)' (43722 KB).................... Done!
Validating download...
Integrity Check succeeded.
Installing package 'OmniSharp for Linux (x64)'

Downloading package '.NET Core Debugger (linux / x64)' (64045 KB).................... Done!
Validating download...
Integrity Check succeeded.
Installing package '.NET Core Debugger (linux / x64)'

Downloading package 'Razor Language Server (Linux / x64)' (57828 KB).................... Done!
Installing package 'Razor Language Server (Linux / x64)'

Finished

OmniSharp log

Details

Post the output from Output-->OmniSharp log here

C# log

Details

Post the output from Output-->C# here

Environment information

VSCode version: 1.38.1
C# Extension: 1.21.4

Mono Information

OmniSharp using global mono :6.4.0

Dotnet Information

.NET Core SDK (reflecting any global.json): Version: 3.0.100 Commit: 04339c3a26

Runtime Environment:
OS Name: ubuntu
OS Version: 18.04
OS Platform: Linux
RID: ubuntu.18.04-x64
Base Path: /usr/share/dotnet/sdk/3.0.100/

Host (useful for support):
Version: 3.0.0
Commit: 95a0a61858

.NET Core SDKs installed:
2.1.802 [/usr/share/dotnet/sdk]
2.2.402 [/usr/share/dotnet/sdk]
3.0.100 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.13 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.7 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.13 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.7 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.1.13 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.7 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
https://aka.ms/dotnet-download

Visual Studio Code Extensions

Extension	Author	Version
csharp	ms-vscode	1.21.4
csharpextensions	jchannon	1.3.0
gitignore	codezombiech	0.6.0
indent-rainbow	oderwat	7.4.0
json-tools	eriklynd	1.0.2
rainbow-brackets	2gua	0.0.6
shader	slevesque	1.1.4
vscode-glsllint	CADENAS	0.0.5
vscode-nuget-package-manager	jmrog	1.1.6
whitespace	sandcastle	0.0.5
xml	DotJoshJohnson	2.5.0

[filipw]

This is a duplicate of OmniSharp/omnisharp-roslyn#1624
There is already a PR with a fix here OmniSharp/omnisharp-roslyn#1625
As soon as the PR is merged, there will be a pre-release OmniSharp that can be used as workaround.