Steps to reproduce:
1. Open the attached project (865975-TestProject.zip)
2. Open the test.unity scene
3. Open script(Assets/TestScript.cs) in Visual Studio and attach debugger to Unity process.
4. Set break point on line 13
5. Press play in Editor
6. When debugger stops on a break point press press "step over" or "step in" three times, so that the debugger would be evaluating line 16
7. Hover over the aa or qq
8. Notice, debugger does not evaluating these variables

Expected result: Variables should be evaluated
Actual result: Debugger does evaluate the variables

Reproduced with: 5.5.0a4, 5.5.0f3, 5.5.0p3, 5.6.0b3
Not reproduced with: 5.3.7p3, 5.4.3p4, 5.5.0a3
Regression introduced in 5.5.0a4

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This issue needs be resolved within Visual Studio Tools for Unity (VSTU). We have contacted them about this issue and they are actively looking into resolving it.