Dodgy is absolutely right!
I haven't heard of any other brand of HPT that the positive line disappears. I have kept all of my HPT's for my babies pregnancies. The oldest one is over 11 years old now and is still positive! The disregarding any changes refers to any positive lines showing after the allotted time. That is a test that was negative at 10 minutes that loooks feintly positive at 20 minutes, often that happens due to the dye interacting with the chemicals. Hcg reacts with the reagent strip of dye so once that occurs the dye should fix and not disappear. It would seem with the faulty tests the dye is reacting with the urine weather it detects HCG or not. This is why the company issued the statement that a positive should remain positive for at least 48 hours. There are many reports on the web of false negatives for this test also. Women report having a negative with this brand and being positive with other brands. I haven't experienced this but these women report that they have.
Receiving a false positive, or a positive and an hour later finding that it is now negative is extraordinarily distressing. The company were meeting on Friday and they called me to tell me the outcome of the meeting but I wasn't home. So, we have to wait until next week to find out.
Let's hope they recall the product so any more women don't have to be affected like this.
Love to you,
Deb