Confirmed in ver. 0.15.7.
I made sure the area was dark, and still no Wither skeletons around nether fortress. Blaze only spawn around spawners. I've currently checked two different fortresses.
It's still there on 0.15.6, Device: Windows 10 edition, tested with spiders
The current workaround for this issue is to quickly run away to an open area say with less non-level surface, and hope that the wolf teleports to you.
Current workaround, when that happens, quickly make your wolf sit down and it'll stop attacking. It won't attack again even after 'standing up' again.
Update 0.15.6:
I won't say it's just when riding horses. It's also mostly happen when there's non levellled surface near where you are. I teleports under my chest in my house
Update: Still there for version 0.15.6
Thank you for the link. I couldn't find a way to ask except here. Now I do. Sorry for the mistake.
This issue affects Minecraft W10 ver. 0.15.4 as well. Hope it'll be fixed soon 😉
Confirmed on the same version on my device.