When you use a 3 dose potion on any potion with space in it nothing happens. The same goes for 2 dose potions in the same regard. Someone did program 1 dose potions to work on 3 dose potions, so perhaps that programming could be used further on the other dose potions.
This has been forwarded to the developers, thanks for reporting it!
Reference: blitz/engine#105
- Flustered