It's because e06319b is using `file-name-split` which will discard the driver name in Windows.

For example:

(file-name-split "c:/Data/projects/notes/techs/.burlIU3pav.html")

# Output: ("" "Data" "projects" "notes" "techs" ".burlIU3pav.html")

Since the driver name is discarded, the constructed URL is "file:///Data/projects/notes/techs/.burlIU3pav.html", which does not exist and cannot be opened.