I created a private sentence for 堪忍 and bound it. It looks fine to me, but it doesn’t show up in the dictionary or in a quiz. I was juggling two devices at the time so I may have left something in an inconsistent state.
Can you take a look? I left the sentence in my studypad to make it easier to find.
I believe what might have happened is the counter for "this user has XX private sentences for this work" got borked, possibly due to the string of actions with editing/parsing it? Definitely not user error, but needs to be fixed at some point.