Incorrect output volume displayed in assembly machine for some railway items

[DuckCity]

Hi
When creating more than one locomotive, or cargo/fluid wagon, in an assembly machine, by manually inputting enough resources for multiple items, when more than one has been made the output volume box incorrectly shows a volume of one. All items can then correctly be retrieved from the machine.
This may also affect other items I haven't noticed.
Thanks

[Loewchen]

It recipe is holding at 100% until the output slot is free, if you free it, the product will be created and put in the slot.