I reported issue this in the Digital Pinball Fans/Zen Studios forum here (first post on page 9):
http://www.digitalpinballfans.com/sh...scussion/page9
(Note that the above forum is an entirely different forum (although it looks the same)...you'll have to create an account there to post there).
I previously had 3 of the 4 high scores on Medieval Madness but at some point (I'm guessing after I purchased the unlocked table pack), my high scores were wiped from the table itself. Like you, they are still in the rankings but they have vanished from the table itself. Again like you, I'd get a new high score on the table and after entering my initials, that score is nowhere to be seen.
Glad that you reported it here because at the thread I mentioned it at the above forum, all I heard were crickets...
You may want to report it there as well and also contact Zen with the issue.
When contacting Zen, do so from the Williams Pinball iOS app itself under the Settings gear icon at the top-right of the home screen:
Settings/Contact Us
This will create an email with your device's info so they can better pinpoint the issue.