Functions v3 - 64bit supported?

#### Is your question related to a specific version? If so, please specify:
3.0.12785.0
#### What language does your question apply to? (e.g. C#, JavaScript, Java, All)
C#
#### Question
When I try to run a function in Visual Studio in x64 I get the following error:

```
[25/10/2019 23:12:00] A host error has occurred
[25/10/2019 23:12:00] System.Private.CoreLib: Could not load file or assembly 'ProjectName, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.
Value cannot be null. (Parameter 'provider')
```

The same function works correctly in 32bit. You can see this behaviour with the default created project from the template. This occurs in both .NET Core 2.2 & 3.0.

Reproduce the default Azure Functions project in Visual Studio using x64 with .NET Core 2.2 and 3.0, then compare it with the working 32-bit configuration. Investigate the reported assembly-loading error and determine whether x64 is supported; done means a confirmed support status, cause, and applicable guidance.

Written by the indexing model from the issue text.