This is a vscode extension that serves as a minimal reproducible example for this bug: treeView.reveal with expand: 3 only expands the first level 3 folder · Issue #181889 · microsoft/vscode

Here we see that if you click on "Expand Item Three Levels" once only the level three folders after the first level two expand. If we click again the rest expand.

Expanding a large folder like node_modules will also make that the promise never fulfills.