on 11/19, davidmj have submitted an additional test to the acp_bbcode module (revision 1.33) which broke bbcodes with parameters.
EXPLAIN:
in order to verify that the bbcode is legal, the new test compare the open and clode bbcode tags, and require that they will be identical.
however, when using a parameter, the open tag is "bbcode=", while the closing tag is "bbcode", so the test fails.

RECREATION:
ACP->Posting->BBCodes->Add new bbcode
add the code from the example on the left ("colour"), and press submit.