There are several reported issues with Save Zones displays in the mobile previewer when the Mobile Content Scale Factor is set to 0.
When MobileContentScaleFactor is set to 0 a couple things happen:
- If you go to the Play button's drop down -> Advanced Settings you will see the settings for resolution. If you choose Phones -> iPhoneX, the resolution will update. However, you will notice that the Safe Zone Preview field says "No Device Safe Zone Set" (as seen in attached image). This is a bug because clearly the preview profile should say iPhoneX.
- If you go to a UMG UserWidget and select Screen Size -> Phones -> iPhoneX, you see in the lower left that the device profile shows up appropriately (iPhoneX), but the custom unsafe zones don't show up at all in the editor. This is a bug because whatever the mobile content scale factor is set to, it should still show the unsafe zones properly.
- If you launch in Mobile Previewer, no safe zones show up there either. The debug bars don't show and the elements on screen are not moved as one would expect.