Hi. New here.
With an wAP ac and Router OS just updated to 7.20.6. Still in 2026, comparation is case sensitive, getting MAC from devices internally in lowercase, and storing ACL rules case sensitive but showing always in uppercase.
You must write you rule in lowercase (lower hexa) but you always see it in upper.
If you writed in uppercase, rule never matches.
I writed “(MAC lowercase)” in each commentary to ensure never forget.