There is no meeting in Brussells where all the scientists get together to discuss the problem of defining species, it is simply that there are sevral ways of seperating genetic prgression i.e. species.
The most common is the most obvious, its day one biology class....when an animal becomes so diverted from its parent species that it can no longer breed with it, it is a new species.
The issue?
In the most true evolutionary form, this is about genes being so different to the original species genes they can no longer procreate. In simple terms, the dna code is so different that they no longer can be read together. Like trying to mash a french book and a german book together.
But some biologists include mechanical restriction too, like a yorkshire terrier not being able to procreate with a greyhound, because it simply can't reach!
There is no actual debate however and no real use for a definition of a species. There is no gold standard or perfect example of a specific species, unless the environment stops changing, which it won't and on top of that all species would have to adopt the same enviroment, i.e. have the same influences to the genes.. then you could narrow it down, but this is hypothetical beyond possible. Environment includes predators, weather, grography, climate etc etc....so many variables on one planet, what is useful to a human here in the UK is not useful to a human in west Africa... black pigmentation and as said, sickle cell for malaria protection.
It isn't that science is in turmoil over the issue, Watchtower used to quotemine as if there was disagreements in science, in reality there is no right answer and the scientists differ depending on their objective. To think there can be a blueprint for a species is to not know or understand biology, specifically evolution. It is a constant variation in all directions, gene by gene, baby by baby... only the enviroment will dictate the most suitable, the fittest.