This can be because it sets a base calculation of the fuel range of the full tank and then adjusts with the MPG average. I know when I fill my sonata, my MPG immediately after filling is low because of stopping and starting to get out of costco and speed up on highway, but in time it balances out to normal levels again. At that point, the Distance to Empty then starts moving for me.
Only objection I have with mine is that on the firmware based on fuel injector dwell and on 120,000 BTU per US gallon gasoline. With this stupid winter gas of as low as 93,000 BTU per gallon, its lying to me. But it it instantaneous, can watch the mileage drop when driving.
Possible problems with all these computers is a slightly lower voltage that is lacking a proper power on reset voltage due to some loose connection someplace. Dates back to the 80's when they started using computers in these things. And may affect just about anything, radio, IP on coming on, heater in thermostat, transmission not shifting properly, car won't start, etc. etc. 0.1 volts low may make a difference.
Problem dates way back father-in-law purchased a new 86 Chrysler with an electronic dash controlled by a microcontroller, one year warranty, went out, dealer replaced the dash.
Went out again after that year, dealer wanted 600 bucks to replace it, brought it over to me, removed the ignition switch, contacts firing that radio were making poor contact, cleaned and bent them, added GB Ox-Gard for protection and lube, dash worked great again, never touched it.
All deals with lack of that all important power on reset or lack of it. Software guys could use a self correcting code to avoid this problem, but sure takes a lot of extra work. Any weak electrical connection can also cause these problems, and every different computer that depends on it can be the weak spot.