I’ve by no means performed this however I’ve now learn the foundations pdf from right here

Firstly I could not discover something within the guidelines that indicated when the subsequent participant would begin there flip! I can solely assume this the identical as [basic Uno rules] in that play passes clockwise after a participant takes a flip.2

The guidelines for showdowns say

The participant who performed the cardboard takes the Showdown unit and locations it
between themselves and the subsequent participant within the present order of play
(except they performed a Wild Showdown Card – extra on that later).

and later

When you play this card, you get to decide on which participant to have a
showdown with

There is nothing in these guidelines which signifies that participating in a showdown is a gamers entire flip. It appears to me {that a} showdown simply occurs with the. subsequent participant in flip order after which that participant takes there flip after.

If it was that gamers entire I’d anticipate the foundations for wild showdown to counsel that play continues from the participant chosen for the wild showdown, which. they don’t.

As a normal rule for video games, if one thing is just not said clearly within the guidelines they it nearly actually is just not a rule.