dotnet --info output:
.NET Core SDK (reflecting any global.json):
Version: 2.2.105
Commit: 7cecb35b92
Runtime Environment:
OS Name: ubuntu
OS Version: 18.04
OS Platform: Linux
RID: ubuntu.18.04-x64
Base Path: /usr/share/dotnet/sdk/2.2.105/
Host (useful for support):
Version: 2.2.4
Commit: f95848e524
.NET Core SDKs installed:
2.2.105 [/usr/share/dotnet/sdk]
.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.2.4 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.4 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.2.4 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
VS Code version: 1.33.1 (x64)
C# Extension version: 1.19
General use (have successfully reproduced on a different WIN10 x64 machine)
Should not disappear. Seems that it's hidden because It's refreshing/reloading or something (my best guess).
Intellisense disappears suddenly

It actually seems to be getting reset once VSCode adds the auto-newline at the end of the file, if you look closely.
Also, similar problem occurs when I have:

My intellisense just disappears, kind of conflicting. I have to be forced to move the mouse where it's not hovering anything for it to work.
Please fix this, as it is super annoying!
Same issue here, and it's been going on for a few weeks on multiple machines running Ubuntu 18.04.
dotnet --info
.NET Core SDK (reflecting any global.json):
Version: 2.2.203
Commit: e5bab63eca
Runtime Environment:
OS Name: ubuntu
OS Version: 18.04
OS Platform: Linux
RID: ubuntu.18.04-x64
Base Path: /usr/share/dotnet/sdk/2.2.203/
Host (useful for support):
Version: 2.2.4
Commit: f95848e524
.NET Core SDKs installed:
2.2.203 [/usr/share/dotnet/sdk]
.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.2.4 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.4 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.2.4 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
(Note same Host commit as original reporter)
VS Code info:
Version: 1.33.1
Commit: 51b0b28134d51361cf996d2f0a1c698247aeabd8
Date: 2019-04-11T08:20:22.771Z
Electron: 3.1.6
Chrome: 66.0.3359.181
Node.js: 10.2.0
V8: 6.6.346.32
OS: Linux x64 4.15.0-48-generic
The only extensions I have enabled are C#, C# Extensions, and Docker.
For me, it only disappears when invoking a quick-fix to import a reference for the first time in a given file (1.35.1 on .net core 3-preview6). Works fine on subsequent try.

Most of the time it disappears faster than on the capture here.
dotnet --info:
.NET Core SDK (reflecting any global.json):
Version: 3.0.100-preview6-012264
Commit: be3f0c1a03
Runtime Environment:
OS Name: ubuntu
OS Version: 18.10
OS Platform: Linux
RID: ubuntu.18.10-x64
Base Path: /home/.../projects/SDK/dotnet/sdk/3.0.100-preview6-012264/
Host (useful for support):
Version: 3.0.0-preview6-27804-01
Commit: fdf81c6faf
.NET Core SDKs installed:
3.0.100-preview6-012264 [/home/.../projects/SDK/dotnet/sdk]
.NET Core runtimes installed:
Microsoft.AspNetCore.App 3.0.0-preview6.19307.2 [/home/.../projects/SDK/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 3.0.0-preview6-27804-01 [/home/.../projects/SDK/dotnet/shared/Microsoft.NETCore.App]
Visual Studio Code
Version: 1.35.1
Commit: c7d83e57cd18f18026a8162d042843bda1bcf21f
Date: 2019-06-12T14:27:31.086Z
Electron: 3.1.8
Chrome: 66.0.3359.181
Node.js: 10.2.0
V8: 6.6.346.32
OS: Linux x64 4.18.0-21-generic
I have this same issue, and can repro on multiple machines and multiple projects. My env:
.NET Core SDK (reflecting any global.json):
Version: 2.2.203
Commit: e5bab63eca
Runtime Environment:
OS Name: ubuntu
OS Version: 19.04
OS Platform: Linux
RID: linux-x64
Base Path: /usr/share/dotnet/sdk/2.2.203/
Host (useful for support):
Version: 2.2.4
Commit: f95848e524
.NET Core SDKs installed:
2.2.203 [/usr/share/dotnet/sdk]
.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.2.4 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.2.4 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.2.4 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
VS Code version:
1.36.0
0f3794b38477eea13fb47fbe15a42798e6129338
x64
C# Extension version: 1.20.0
VS Code Settings:
{
"editor.renderControlCharacters": true,
"files.defaultLanguage": "json",
"window.restoreWindows": "none",
"editor.renderWhitespace": "all",
"editor.maxTokenizationLineLength": 50000,
"workbench.editor.enablePreview": false,
"omnisharp.enableRoslynAnalyzers": true,
"omnisharp.useGlobalMono": "never",
"editor.snippetSuggestions": "bottom"
}
Same here, would love a fix.
@cloudrex It's difficult to tell what's happening in that gif. Can you explain the problem in words?
@rchande I'm repeatedly pressing CTRL + . to bring up the intellisense and it suddenly goes away.
Most helpful comment
For me, it only disappears when invoking a quick-fix to import a reference for the first time in a given file (1.35.1 on .net core 3-preview6). Works fine on subsequent try.
Most of the time it disappears faster than on the capture here.
dotnet --info:Visual Studio Code