To reproduce:
1. Open a Collab-enabled project.
2. Make a small change (ie, add a material, edit a published scene, etc.).
3. Open the Collaborate window.
4. Make sure All changes are selected and press the Publish button.

Expected: Changes are published with no errors in the Console.
Actual: Changes are published but in the Console the following error is displayed:

InvalidOperationException: {"code": 18, "detail": "Operation is already running"}
Unity.Cloud.Collaborate.Models.Providers.Collab.RequestPublish (System.String message, System.Collections.Generic.IReadOnlyList`1[T] changeEntries) (at Library/PackageCache/com.unity.collab-proxy@1.3.8/Editor/Models/Providers/Collab.cs:477)
...

Reproducible in 2020.2.0a16, 2020.2.0a18
Not reproducible in: 2020.1.0b17, 2020.2.0a15