Yeah… NFC Tools isn’t the best at handling tags protected with Dangerous NFC. I’ve contacted them several times about it, but they apparently don’t care to ensure their app correctly follows the NFC standard.
You can try to use the Dangerous Things Support Tool and write a blank NDEF record to your tag… then power cycle your phone. Doing these two things seems to resolve the issue for most people. If that fails, then try using TagWriter instead.