Word or phrase for 'a much hyped discovery which later turns out to be insignificant or of no value'

In the company where I worked before, the team of specialists which handled customer dissatisfaction issues often came up with seemingly brilliant solutions which would initially appear to be key breakthroughs but would later turn out to be no more brilliant than those which had been tried and abandoned before.

Along those lines, let's suppose, someone is working on a big scientific discovery or breakthrough, it's got big hype and everything, but once it is made known to public and its applications are discussed, people notice nothing useful about it and dismiss it as nonconstructive or nonfunctional.

I am interested in knowing if there is a word or phrase to describe the idea.

(Edits made to rephrase some sentences)

Solution 1:

You could also consider the phrase damp squib, which refers to a wet firework that fails to go off, and by extension anything that fails to meet expectations.

Solution 2:

flash in the pan

It's a phrase which goes back to the 17th-18th centuries, when flintlock firearms were discharged in two stages: a small priming charge in an external “pan” was ignited by a spark from the flint, and the resultant flame was supposed to travel through the touch-hole to ignite the main charge, behind the bullet. Often, however the charge in the pan fired but failed to travel, and the result was a misfire – a “flash in the pan”.

The phrase survived long after flintlocks were superseded, and is still in use today, although declining.

Solution 3:

One could say it did not live up to the hype

live up to : To prove equal to

hype
1. Excessive publicity and the ensuing commotion: the hype surrounding the murder trial.
2. Exaggerated or extravagant claims made especially in advertising or promotional material "It is pure hype, a gigantic PR job" (Saturday Review).