I've noticed throughout the development cycle of 1.13 that End Cities spawn extremely very rarely. This is NOT a duplicate of the bug that was fixed in 18w20a (MC-125615) which fixed it so End Cities are no longer cut off - In a nutshell, when I travel to the End in my snapshot world (currently on 18w20a) and I try to locate End Cities using the "locate" command, they ONLY ever seem to generate in negative co-ordinates (e.g. X -2000, Z -2000) and never in positive co-ordinates (e.g. X 2000, Z 2000)

Steps to reproduce the bug...

1. Generate a new world in 18w20a and go to the End
2. Teleport to any positive co-ordinates you can think of (example X=2000, Z=2000)
3. Try to use the "locate" command to locate an End City. You should find that the locate command cannot locate any End Cities nearby
4. Try instead to teleport to any negative co-ordinates you can think of (example X=-2000, Z-2000). You should now be able to use the locate command to find End Cities.

The attached info-graphic should help provide a visual representation of what's been happening.