C3 is working correctly, it's the logic that a wrong.
every 4 seconds "centre" is playing so it switches to "right", then immedialty it executes the code below, since its now "right" this condition becomes true so it changes to "left", then does the same for "Centre" again.
You could try,
every 4 seconds... set variable to 0.
(sub events)
animation centre playing AND variable = 0, set animation to "right", set variable to 1.
animation right playing AND variable = 0, set animation to "left", set variable to 1.
animation left playing AND variable = 0, set animation to "centre", set variable to 1.
setting the variable to 1 stops the line below from becoming true until another 4 seconds pass.
Thank you!
Oh and sorry I didn't mean to imply I thought it was a Construct 3 problem, I knew it was completely an error on my part. But again, thank you!