If both are the same model and both have the same issue, there must be some kind of manufacturing defect with causing this problem. It's possible that there is a bad batch of electronic control boards, or a common defect causing washers not to reach the proper spin speed in order to dispense the softener.
NOTE: New electronic washing machines needs water pressure to both sides HOT and COLD to work and dispense properly.
I would recommend returning the washer for a refund, because you'll likely see the problem again if you exchange it if it is a bad batch for that model. I suggest buying a Kenmore instead: sears.com/appliances-washers-dryers/b-1320301405?Brand=Kenmore&filterList=Brand&shipOrDelivery=true&subCatView=true&searsTab=true
Our Kenmore top loaders (expect for 29142) are made for Sears by Whirlpool, but use different controls boards than similar Whirlpool models, so you shouldn't experience the same defect. If by some stroke of bad luck you have any problems with a Kenmore, you can call Sears Home Services at 1-800-4-MY-HOME for a Sears Technician to come out to your house under warranty to see what the issue could be.
Unless you posted this too, I did find another person with the same issue with a Whirlpool washer from a couple of weeks ago: applianceblog.com/mainforums/threads/whirlpool-washer-wtw5105hw2-not-dispensing-fabric-softener-at-all.86745/
As well as some comments (scroll down to see them) here that say the same thing: manua.ls/whirlpool/wtw5105hw/manual
Hope this helps!