Add file above/below, Rename file do not work on .NET Core 3.1

[hectorchu]

Describe the bug
Normally its possible to add a new file to the project by right-clicking an existing file in Project References in the Solution Explorer, and choosing Add file above or below. If .NET Core 3.1 is installed this no longer works as intended. The file is created but the fsproj is not updated.
Rename file is also bugged and does nothing.

To Reproduce
Steps to reproduce the behaviour:

1. Install .NET Core 3.1
2. Open existing project containing some files already
3. Right-click on an existing file and choose either to add file above/below, or rename file
4. Observe that the operation does not operate as intended

Expected behaviour
It should do what was intended.
It should work as it did on .NET Core 3.0.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment (please complete the following information):

• OS: Windows & MacOS are both affected.
• Ionide version: 4.5.0
• VSCode version: 1.41.1
• dotnet SDK version: 3.1
• mono / .Net Framework version: n/a

Additional context
Add any other context about the problem here.

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[dkpsk]

This issue might be same as #1297

[Krzysztof-Cieslak]

Duplicate of #1297