I’ve used them exclusively for all 5 of my pregnancies: 1 live, missed mc, chemical, missed mc, currently almost 25 weeks. You will eventually get your peak, I always had high fertility for 2 or more days before peak
I haven't tried Clearblue, but it's possible to see "high fertility" for a few days before getting "peak" fertility." It might be due to hormonal fluctuations, and miscarriages can definitely throw things off. I have been using Inito, which measures actual hormone levels. It has an app that predicts your fertile window and confirms ovulation, so you don't have to interpret anything.
I used them for all 3 of my pregnancy’s (2 miscarriages) and found them to be accurate. I don’t just read the digital, I’ll actually pull it out after the digital result to review the darkness on the lines. I’d wait one more day and also test twice a day for maximum accuracy, once in the morning once at night. I can’t speak to the ovulation the following month as I took a short break after both miscarriages