[Bug] Unable to create a listener

**Bug**
I am unable to create listeners (and no error appears)

**Describe the feature request or bug**
I installed Covenant on my Kali machine. I first installed DotNet 3.1 (sudo apt-get install -y dotnet-sdk-3.1) and then installed Covenant (git clone --recurse-submodules https://github.com/cobbr/Covenant).

When starting Covenant I see:
```
warn: Microsoft.EntityFrameworkCore.Model.Validation[10400]
Sensitive data logging is enabled. Log entries and exception messages may include sensitive application data, this mode should only be enabled during development.
Covenant has started! Navigate to https://127.0.0.1:7443 in a browser

```

Then I can create a username and password through the GUI and login. After that I want to create a listener. I can enter the listener details and click on "create". Then I am returned to the listener overview page without error. The overview page is blank and no listener is created. Also the console shows no additional errors.

I tried different ports (reserved and non-reserved). I also tried starting as Sudo. But nothing changes the behaviour. Then I tried different DotNet versions. But still no change in behaviour. Also tried different browsers / rebooting / deleting cookies etc.

No matter what I do... all seems to work but unable to create a listener.

**To Reproduce**
Steps to reproduce the behavior:
Just create a listener....

**Expected behavior**
The listener to appear after creating it

**Screenshots**

**Covenant Server Information:**
- OS: Linux kali20202 5.7.0-kali1-amd64
- Docker or Native: Native

**Browser Information:**
- Browser: All
- Version: All

**Target Information (System that implant is running on):**
- n.v.t.

**Additional context**