The flavor disappeared
Updated
The batch smelled wonderful while you poured it and smells of nothing three weeks later.
Strong in the pot, gone in the tube
Almost universal in a first attempt, and almost always a process fault rather than a dosing one. The instinct is to double the flavor, which produces a batch that is harsh at first and still fades.
Where it went
Added too hot. Flavor compounds are volatile by definition. Stirred into a melt at full temperature, the top notes leave into the room, which is why the kitchen smells so good.
Held warm. Every minute between adding flavor and pouring costs you some.
Oxidation. Citrus and other light notes degrade on the shelf even when they were handled correctly.
Nothing to taste. Aroma without sweetness reads as weaker than the same aroma with a little sweetener behind it.
Fixing it
Take the melt off the heat and let it fall towards pour temperature before adding flavor. Stir gently rather than beating air through it.
Pour promptly once flavor is in, and cap once set: the cap is a lid on the headspace.
Consider a small amount of lip-safe sweetener, which usually solves what looks like a strength problem.
And weigh the flavor. "A few drops" is not a specification and is the reason batch to batch varies more than the recipe suggests.
How to judge it
Not at the pour. Judge a week later at room temperature, from a capped tube, against a reference tube of the approved batch.
Judging at the bench with the melt in front of you overstates every formula, which is how a balm that reads as strong in the workshop reaches the customer as nothing at all.