OS: Windows 10 Pro
Processor: Intel Core i7-6950x
Memory: 64GB DDR4
Graphics: eVGA GeForce GTX 1080 (Drivers: 390.77)
Java: 1.8.0_25 64 Bit
When trying to return back to the centre End island from the outer End islands, using the End Return Portals teleports me between itself and another End Return Portal nearby. They don't teleport me back to the centre End island like it's intended to.
The attached video should explain the situation more clearly!