My understanding is that auditory hallucinations are more common in schizophrenia which makes this more of a WTF.

Aphantasiac here so this raises an obvious question. Cursory search suggests visual hallucinations due to drugs or schizophrenia are reported. Conscious and involuntary visualisation seem to be somewhat independent.

As I said in another thread, visual hallucinations (without intoxication) are certainly a thing, but they are quite rarely associated with schizophrenia. There is far, far more to the condition than hallucinations or even psychosis more generally, but hallucinations are most commonly auditory