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Dual fuel tank issue


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I have a 2016 GMC LML C&C with a dump bed and dual fuel tanks. I bought it about a month ago and noticed that the front fuel tank was never dropping. Now, after putting a couple thousand miles on I can definitely confirm this is the case. My fuel gauge still moves like it should (not erratic), but it will be on E, and when I go to put fuel in, the back tank is empty but the front tank never takes more than a gallon or so. I’ve been reading that these trucks have issues with the transfer pumps. Although if the fuel is transferred from the back tank to the front tank and then to the motor, wouldn’t that mean the transfer pump is working? Could it possibly be a bad level sensor in the front tank showing E when it’s full? Any help would be greatly appreciated! Thanks
I don't have any experience with LML's or manuals for anything that new, but tgat is how all the older models work. Normally if a sender is even the slightest bit flaky or not moving right, it will set a code and put the gauge straight to empty.