Brief and simple
1. We do not calculate the percentage of the drive health. The SSD itself calculates it and gives it to us. Or in other words, this data comes from the manufacturer of the drive.
2. The estimated lifetime is calculated depending on the amount of data written to the drive. If it is not calculated yet, it means that little data has been written to it. Simply wait a bit, it does not usually take more than a week (or two) after the first launch of the program.