Reproduction steps:
1. Open customer's attached project in "GraphView.zip"
2. Go Window -> Analysis -> Asset Dependency Graph
3. Select "Directional Light Variant" in Assets
4. In Asset Dependency Graph press Explore Asset button
5. Enter "C" in the Asset Dependency Graph search bar

Expected result: all Assets that contain string "C" in their name string will be highlighted
Actual result: some of the Assets chosen randomly are highlighted (deleting and re-entering "C" will always produce different results)

Reproducible with: 2019.4.8f1, 2020.1.2f1, 2020.2.0a20
Could not test with 2018.4 because GraphVew is not available

Notes: this can be resolved by executing each on graphEelements.ToList() instead of on graphEelements (this can be done in AssetDependencyGraph.cs by commenting line 100 and uncommenting line 101)