Vertical slides 'fade' instead of 'slide' while transition style is on 'slide'

[GamuIsAlreadyTaken]

Describe the bug
Pretty much the title,

• Transition style config = 'slide'
• Expected: Vertical slide transition to be 'slide'
• Observed: Vertical slide transition is 'fade'

Samples to Reproduce
I don't know if its enough but, with default settings (I've just discovered them) this md:

# There is a bug
---
# With vertical slides
--
# Should move but it
--
# Fades...

should show the bug, at least it... does on my machine 😅

Expected behavior

Vertical slide transition should be 'slide'

I've tested a bit with other transitions and seems to be just broken on 'slide'

Observed behavior

edit: