It turns out that if the Device ID = 0x0000, every frame is treated as an ID frame because the CRC is good for all of them. In fact, a valid ID frame also has '00" for the low order two bits of the LSB.
(My March, 2017 Blueline sensor's out-of-box Device ID was 0x0000, naturally.)
The easy workaround is to hold the sensor's reset button for 10-ish seconds to force it to assume a new ID.
It turns out that if the Device ID = 0x0000, every frame is treated as an ID frame because the CRC is good for all of them. In fact, a valid ID frame also has '00" for the low order two bits of the LSB.
(My March, 2017 Blueline sensor's out-of-box Device ID was 0x0000, naturally.)
The easy workaround is to hold the sensor's reset button for 10-ish seconds to force it to assume a new ID.