If you add an exposed public & editable variable to a blueprint and then click on an instance of it in the level map, the new variable is not visible. In previous versions it would be immediately reflected. Now you have to restart the editor before it will display.
Make sure that you are compiling the blueprint. This will make sure that the variable appear in the Details panel. If they still do not appear, click off of the blueprint in the level and then select it again. There is an issue in Preview 8 that causes this and it has been entered as JIRA UE-10298 in our tracking software.
Yes, I already did all that stuff and it didn’t help, only a restart of the editor fixed it. But if you already have a jira to address it, we’re good.