[2.0.32] Hi everyone, several hours I am trying to figure out those freaking thrusters. I have 4 issues currently with them, first time using them in my life btw.
Must say though that in about 10 years of playing Factorio this is first game breaking bug for me, so I try to stay calm

1) UI does not match game mechanics - visual fluid markings do not correspond with how the game actually behaves. This is confusing, as there are 4 input/output points on a thruster, 2 marked as oxidizer and 2 as fuel, but all 4 work (or currently do not properly work) for both
2) fluid mixing/replacing - as in the ThrusterFluidMix.gif, this was my first time connecting thrusters and I wanted to do the logical thing - I got fuel connected to left thruster to upper fuel joint, so I wanted to connect oxidant to the right one to upper water joint, as it was close by and easy.. (then I wanted to figure out how to connect fuel to right and water to left one, before I even knew the thrusters transfer fluid with each other, I though I would need to plug them all in separately)
3) behavior is inconsistent - this makes the issue even worse, as the fluid mixing is inconsistent. Sometimes I construct same layout with different results - see attached videos, when once fuel got replaced by oxidants, once it was not - and I did the same thing.
4) not filled thruster - when used 2 thrusters besides touching each other, only the left one is being filled, the right one works only as a fluid transfer medium - gif attached - NotFilledRightThruster.gif (note: this was confirmed during my first flight, only left thruster was working)
And when I try to fly it I should worry that it will switch mid-flight as others say?
It would be greatly appreciated if this is fixed to at least work consistently, so that we can build around that. Never expected bug this big in Factorio, such great reputation it has

Edit: adding a savegame file.