Why is a one letter wildcard search not hitting the index?...yet if you add two or more letters to the wildcard, the index is used.  Yes cn does have 3 indexes on it.

Example
26/Feb/2021:16:33:51.189998029 -0600] - NOTICE - ldbm_back_search - Unindexed search: search base="cn=users,o=Xxxxxx,O=Xxxx" scope=1 filter="(cn=a*)" conn=3 op=18

Yet if the filter is ab* it uses the index