Hey Droll,
Sorry for not being clearer: I stop the fuel production at Earth. The tankers don't unload any fuel on Earth. Step-by-step,
they're in Uranus (which has sorium), fuel at 100%, go unload fuel at earth,
the trip from the gas giant lowers their fuel to 99%,
they go back to the gas giant,
get their fuel to 100% from mining,
hang around there for a couple of months,
and the cycle begins anew
the total amount of fuel at earth never changes, though the fuel harvesters should be transferring it there
EDIT, to address what Energyz said in the bugs thread (so just copying what he said, and what I said there):
You need to check tankers in class design, that'll fix it. But I think it's a bug too
Hey Energyz,
Tried your recommendation, both by
unlocking existing design, changing to tanker and locking again,
and by creating a new one from scratch, building it and setting the harvester transfer and return routine,
but I'm still getting the same behaviour (they refill at the gas giant, go to Transfer Fuel to Colony, but don't transfer any fuel whatsoever)
so still happening
EDIT 2, for whomever might get stuck in the same issue from not reading the Changes discussion: just add an Refuelling system