Oxford-Hachette french-english dictionary no longer looks up conjugated words on iPad

Since upgrading to iPadOS, the behavior of my French-English dictionary has changed. It no longer looks up words that have been conjugated or modified. It does not recognize a word as common as “sont”. It will not even look up words that have been pluralized. This makes it almost useless. Is there anything to be done about it?

Updating the iPadOS did not help. I am now on the most current version 13.4.

The dictionary on my iPhone, which is still on iOS 12.2, works just fine.