Please open a support case.
Troubleshooting lack of client placement requires logs and some xml output which TAC will be able to extract.
Some additional information that helps:
How many floor plans do you have in VRF? How many AP/Devices monitored by AirWave? How many clients (average) on your network? When you noticed the behavior, was it during peak client activity on the network? What types of network devices are in your deployment? If you have Aruba devices, do you have AMON setup to help gather location data (AMON allows for transmissions of location data at 1 minute intervals as opposed to SNMP polling limitation)?