Quick answer: Godot 4 input actions missing after importing a project from a different OS? File case sensitivity on Linux strips Windows-authored input map entries - re-save project from Linux.
Imported Windows project on Linux; input actions empty. project.godot file looks correct.
Re-save the project
Open in Linux editor; save. File is rewritten with Linux-compatible paths/casings.
Verify project.godot parsing
Cross-platform projects need [input] section parsing on every OS. Spot-check the file after migration.
Use forward slashes
If you have any custom paths, forward slashes work everywhere; backslashes don't.
“Project files are text but not platform-agnostic. Cross-OS migration is a real workflow.”
If your team mixes Windows and Linux, decide on one as canonical. Migration becomes one-way; bugs are eliminated.