Completion is not working when there is backquote

### Description

Hi,
When I run the example from [fslab](https://fslab.org/getting-started/), the completion is not working when there is some backquote.

### Repro steps

There is two examples, which one is working and the other is not.

https://imgur.com/2RhW8Wa

https://imgur.com/zVdtMLu

### Expected behavior

Completion with backquote should work.

### Actual behavior

Completion doesn't work.

### Known workarounds
None

### Related information

* macOS High Sierra 10.13.6
* Emacs 26.1
* dotnet 2.1.400, Mono 5.14.0.177

Thanks.