[chirp_users] Baofeng UV-6 "refused to send second block 0x1ec0"

While attempting to run the initial download for a group of new recently received Baofeng UV-6 radios, all are responding with “radio refused to send second block 0x1ec0” right at the tail end of the download... I’m using the most recent CHIRP build for Mac. I’ve attempted multiple Macs, no difference. I’ve attempted older 2017 versions of CHIRP, no difference. The cable I’m using works for other Baofengs, including UV-6 units we purchased 5 months ago, just not these particular UV-6 units. These units are clearly labeled UV-6 (not UV-6R). Tried the UV-6R setting just in case, but the download didn’t start. Any suggestions?

-Charley KE4QBW