So I feel like I'm doing Zenimax's job on this one, but the failed transfers and loading screens were becoming a real pain in the ass esp. on bosses and storyline quests.
A simple fix considering SavedVariables does the trick, pretty much the same stuff blizzard did when they ask you to delete your wtf/wdb folders or run repair. Anyhow, navigate to your elderscrollonline folder in my document, pick live or liveeu depending on your region. Open the folder SavedVariables and delete the file ZO_ingame.lua. Launch ESO and login. You will likely crash the first time, reboot ESO. In many cases the dirty data is now purged and your loading screen issues will be fixed. If not, contact support and let them know you already deleted this file - It will let them get out a fix faster.
Enjoy and take care