As can be seen in the image. I have a ship outside of mine range but in range of tanker. The Energy storage isn't full and the ship is generating less energy than what's being used. For some reason however it's not getting resupplied.
I've encountered this occasionally in the past but forgot to post here, no idea how it works.
Playing on Steam version 1.1.4 (Beta is toggled in options, if relevant).
Using Windows 7 Home Premium on a desktop. See DXDiag.txt for full info.
EDIT: Interestingly enough, letting it play for a little longer, the resupply starts and stops as needed to prevent the ship from dropping below 500 energy. This leads me to believe it's due to the larger ship having a relay. In chains of tankers, they only pass on energy if a connecting relay ship has less stored. My conclusion is that the matter is this being a gameplay, but not game-breaking bug.
The resupply priorities are hard to get right for all cases. At the moment, energy is balanced between ships as an absolute rather than relative quantity. When that ship reaches less than 550 energy, the tanker will start supplying it.
V has tried to get the priorities correct for ships with/without on-board generation, Guppies, ports of their own, combinations of ships inside/outside mine range, energy deficit, and varying numbers of tank modules. There is no one answer, and a manual-control system would take it from bad to worse.
Also, the game was built with the idea that a Varro would be unsustainably large. So 6000+ energy capacity is a fair distance from the designed size.
I figured out as much shortly after posting, good to know I wasn't imaging things and it's indeed a "feature".
All things considered it's fair how it works and can even be written off as "balancing" although raising awareness never hurts!