Weird issue when we apply an ACL to a VLAN interface we are noticing that the counters are not incrementing correctly or are taking some time ot increment. (Example line with known constant traffic is not incrementing but check it an hour later and the counters have incremented but not as much as expeceted. We are seeing this accross multiple platforms and ACL.
Did you try:
ip access-list update-threshold 1
ip access-list update-interval 1
THe above will update every hit.
Let me know if this solves your issue,