Pretty much RfidResearchGroup/proxmark3#138 but for Chameleon Ultra.
I suggest an option to ignore incorrect BCC when selecting tag. Could be a parameter for hf mfu or hf 14a raw, or a config value.

The way i encountered it - i have a chinese Ultralight tag with partially written UID, which results in CU reporting BCC error when attempting to communicate with the tag, otherwise the tag is fine. Fixing the tag is just a matter of fixing the BCC, but currently it's not possible, and writing to the tag without selecting it seems to do nothing.