I apologize for this delayed reply to your gardening question and hope it is still helpful to you.
That's very strange. I am not familiar with that condition on passionfruit. I suggest you take a sample of the fruit to your County Extension Office for them to look over and diagnose. Their services are usually free hand a local expert may be familiar with the condition you are describing.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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