Symptoms
OOB Autocomplete control in K2 smartforms Control Pack 4.6.9 does not work properly when the initialization rule is disabled and the Live Search is enabled when using it with ADService2, ADUsers GetUsers Method (SQL as well).
Diagnoses
This is known issue with OOB Autocomplete control in K2 smartforms Control Pack 4.6.9
Resolution
Contact K2 support to obtain coldfix for this issue or upgrade to the newer version of K2.