A previous upgrade of Horde (~1.5 years ago) was even more lossy, if this provides any solace at all. All filters and settings virtually vanished. It's a 'Horde thing'. But they have improved.
One of the Horde developers answered an enquiry of mine in the mailing list. He said that it might be worth asking the host filters that have the "is" condition (not just "contains" and "not contains") are a possibility. It's not really important to me, but I thought I'd ask anyway.
Best wishes,
Roy