Blocks move when a project is reloaded

[martinwork]

Describe the bug

Arising from support ticket https://support.microbit.org/helpdesk/tickets/82439 (private)

After creating a project with blocks neatly aligned, the blocks move in an apparently unpredictable way when the project is reloaded.

The movement seems to vary - does it depend on which block was moved last?

The moving blocks move across more on each reload.

I don't know if functions are essential - but the example in the ticket has functions.

To Reproduce Steps to reproduce the behavior:

1. Go to https://makecode.microbit.org/_hLc2Ve1zYbEz
2. Position blocks as below
3. Visit Home and reload the project
4. See error

Expected behavior Blocks don't change position.

Screenshots Before reload

After reload

micro:bit version (please complete the following information): not hardware related

Desktop (please complete the following information):

• OS: [e.g. iOS] Windows 10
• Browser [e.g. chrome, safari] Chrome
• Version [e.g. 22] 128