Doesn't that just drive you NUTS!!!!I feel your pain. I had similar struggles with plum jam today.
It's a Ball recipe I followed. No matter how long I boiled it would not reach the temp stated in the book. In the end it started to set IN THE POT! It was supposed to yield 6 half pint jars. I got 3.
Round 2 was similar but I went ahead and water bath canned it earlier. Yup it did not set properly.
I will call it plum syrup and leave it as is.
Tomorrow I will attempt with strawberries. That recipe calls for pectin.
OH I saw italian plums today at the market and forgot to grab some. I want plum jelly!