Sometimes the Chip is moving. Unfortunately nobody can say in which direction.
For older dogs it always helped me to start with ‘Read ASK’ from the left shoulder, near the neck and go back until the LED goes yellow. For long fur it goes more often yellow, but after scanning twice, you’ll get a feeling for false positive.
Right now (with a lot help from my wife) I was able to scan every dog.
And a friend of mine, in the Tattoo and Beauty business was so interested in Flipper and now got registered for human NFC/RFID implants… Soon I can start scan myself