- Name all your assets explicitly: Go through your sprites, variables, and kinds, and give them clear, unique names right away. This seems to help prevent automatic cleanup or deletion by the editor.
- Clean up duplicates and unused items: Before saving or reloading, delete any duplicate assets (e.g., multiple copies of the same sprite) and replace them with a single, named version. Avoid using the “duplicate” function if possible, as it can trigger the issue.
- Save and backup frequently: Use the version history feature in MakeCode (under the project menu) to revert if things go missing. Also, consider exporting your project regularly as a .png or .mkcd file to have backups outside the editor.
- Reload carefully: If you notice things missing after a reload, try undoing (Ctrl+Z) immediately or switching between blocks/JavaScript views, which sometimes restores them.
- Test in a stable environment: Ensure you’re using the latest stable version of MakeCode (not beta), and try a different browser if you’re on Chrome/Edge—some users report fewer issues in Firefox.
If this persists or you can pinpoint steps to reproduce it (e.g., specific actions like deleting a block or adding a new sprite), it would be great to share more details on the official MakeCode forum threads discussing this, such as these ones for visibility and potential fixes from the devs: