Mark Knowles wrote: Whilst on the surface Voynichese might appear to be very different from ciphers of that period that doesn't mean that it isn't a closely related form of cipher, though different in some respect(s).
I don't think it's the surface that makes the Voynich text different. Medieval cipher glyphs are quite varied, almost anything goes in terms of shapes. In fact, most of the people who claim solutions, and many of those who present research findings, are treating it as they treat most medieval ciphers, as a substitution problem, as a cipher alphabet. They make charts the same way charts are made for other cipher alphabets with the VMS glyphs on the left and their natural-language "equivalents" on the right.
Superficially, the VMS text does look to many people like a language, or a ciphered version of a language. In fact, a high proportion of the substitution charts treat vowel-like shapes in the VMS as vowels in their claimed solutions.
But under the surface, the glyphs are not organized the same as natural language, and this is the part that is frequently overlooked. If this were noticed by all the people offering these charts, they would have done more research before assuming it was a substitution cipher.