Which Xojo IDE and Xcode version prior to 2018r3 works best?

Hi iOS folks,

I need to build an app that will be for enterprise distribution (i.e. NOT pulled through the App Store). It must support back to iOS9 and the iPhone 5 and SE screen sizes.

I’ve already discovered that anything newer that 18r3 is not a good choice, and I’m discovering serious layout issues with 18r3 (multiple selected controls landing on top of each other when repositioned with the mouse …).

Which version of of the Xojo IDE prior to that and which associated version of Xcode would be my best option?