I am using a lot of custom ui's and have had the black screens before but was easily fixed using the information I found in the forums.
This time nothing I have tried has worked. The only screen I am having a blank screen on is the zone re-use timer screen. It's been like that ever since the update came out to include it.
In your Custom-UI-Direcrory should be a file named: eq2ui_mainhud.xml
Open the File in an Editor und look if there is the following line:
<include>eq2ui_mainhud_zonereuse.xml</include>
If the line is missing, insert it before the line:
</Page>