Vishve Devah means all the gods, and a large group of hymns in the Rigveda is addressed to them under that name. The difficulty is immediate and it has never gone away: those same hymns then go on to invoke Indra, Agni, Mitra, Varuna and the rest by name, sometimes in the same verse. If the Vishvadevas are all the gods, the poet is calling on a set and then on its members, which is not obviously incoherent but is not obviously a totality either.
Two readings are in circulation. On the first, the name is a ritual catch-all and the point of it is completeness. A sacrifice is a distribution, an offering left undelivered is a grievance, and a formula that says all the gods ensures that nobody who should have had a share is left out, including gods the officiant has not thought of and gods with no name. On the second, the Vishvadevas are a class in their own right, one group among the others, whose collective character is what the hymns to them actually describe, and whose name is a description of that character rather than an inventory.
The hymns can be read either way, which is why the question is old and why the atlas marks it as argued rather than settled. It is also a question that matters beyond this one entry, because it is a question about what a Vedic god is. If a name can be both a category and a member of the set it names, then the pantheon is not a list of individuals with a boundary around it, and a good deal of the trouble modern readers have with Vedic religion comes from expecting that it is.