I had an oxidizer tank set to high priority, and once the rocket had launched, I noticed duplicants continued to deliver oxylite to the tank (now invisible) even while it was in space. The inventory appeared to increase if you checked the rocket in the starmap while in space, but it appeared the oxylite was lost once it landed. It's possible the other tanks receive fuel while the rocket is in space as well, but I didn't test them thoroughly.
Additionally, if the oxidizer tank isn't set to max capacity (2700kg), every time you click on the tank, all of the oxylite is immediately dropped on the ground. Duplicants also ignore the capacity when filling it with oxylite, always putting in the full 2700kg, no matter what it is set to. There also appears to be no way to specify not to bring oxylite if you wish to fill the tank with liquid oxygen. Perhaps there should be separate bars for oxylite and liquid oxygen capacity?
Steps to Reproduce
Occurs during normal interaction with oxidizer tank.
This issue has not been confirmed by a developer yet.