Hey there! Think we get this question a bit so I will take a shot at suggesting try using
scene.useRightHandedSystem = true
Also feel free to send a playground link with this directly so we can take a peak. 
Here are a couple different threads we have on the topic:
(Texture Flipped in Playground Instances but Not in Sandbox.... Why?)
Why Is My Dynamic Text Texture Got Flipped Horizontally? Also How To Make It Transparent?
(I also have a cube demo I will look for as well)
Also wondering if this needs to be added somewhere in the documentation if it’s not already.