Am I alone to be unable to correctly tween the simplest shape ever?
(iMac 27'' 5k 2017, Mojave, Animate CC 19.2.1)
Start with "a" in the upper-right corner and place the rest of the shape hints counter-clockwise.
No, I don't know why this works.
It blows my mind that after more than a decade shape tweens still don't work properly.
Go and tween a path in After Effects and you'll be aghast at how bad it is in Animate.