Oh. This type of seedling failure is usually culled. It IS a defective plant and your should be able to claim a refund or replacement.
For the last three years or so, I used to see at least 3 or 4 of these -- sometimes called "blind" seedlings because they have no "eyes" (please, no offense meant) -- most often happens in the seedleaf stage, when no growth buds develop and the poor plant pumps all its efforts into growing what its got -- so the seedleaves or the only trueleaves grow huge and thick and leathery.
I only had one of these this year though.
Since yours has grown to trueleaf stage, it *might* be possible to release it from the trapped state it's in by cutting off the top leaf. Another *maybe* technique is to injure it, by making a slit on the stem with a sharp razor.
The idea is to force the plant to generate a growth bud, if it is capable of doing so. Injury or cut on the stem ABOVE the seedleaf scars would initiate appropriate cell production IF it is capable of it.
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