[Bug]: Transport randomly drops all the units instead of selected ones

### Describe the Bug

Transport randomly drops all the units instead of selected ones
Not sure is this only sera transport issue or regardless of race, but atleast for sera it was noticed by me and also tested by YungDookie which also faced it in sandbox

### Reproduce the bug

Take some sera transport, some engies, use shift to drop some engies in different places, at some point transport will drop all engies instead only selected ones

### Screenshots

Video by dookie:

https://github.com/user-attachments/assets/d00cb7c6-8383-48a9-b93a-3e125e26924f

### Additional context

_No response_