Unity UI Layout Group not working after Unity 2018.2 to 2018.3 Upgrade

I have a very simple Vertical Layout Group, it's just 1 column of buttons one below the other. After upgrading to Unity v2018.3.5f1 when I hit play in the editor and go to that menu the buttons are all messed up. 2/3rd of the buttons aren't showing, also a button which is actually anchored to the bottom of the canvas group is now in the middle of the screen.

Yet when I look at that same UI menu in the editor it's layout is just fine, just like it was in v2018.2.8f1 before I upgraded Unity. Anyone else had this happen to them?
I've also got another UI button which was Top Right of screen (and lives in a different Canvas Group), now appears dead center of screen when I build for Android. (the Vertical Layout Group is also messed up on Android, just like in play mode)

Any suggestions for debugging this?

 

Same problem here. Did you find a solution?

 

Did you try to remove and readd the component and see if it is the same behaviour?