If you are missing data from some Client agents, please check the LAST SEEN time of those agents in System - Users or System - Computers.
Also, check if the firewall is blocking the Client connections - ‘Which addresses and ports should be whitelisted on the firewall?’
Additionally, check if the Client agent is installed on the computer - wemonc.exe, wesvc.exe should exist in this folder: C:\ProgramData\{E0E95C6C-F194-4846-928D-E5538022226D}\
Try checking if the agent is running on the computer by cmd - tasklist command - wemonc.exe, wesvc.exe processes should be listed. 
Finally, please check all antivirus logs related to this folder or these files: wesvc.exe, wemonc.exe, sh32.dll, opt.ini.
If you're sure that a PC is ON and the Internet connection is fine, but it was not being tracked by Controlio, please submit a ticket and attach the general debug log.
P.S. The recorded data is uploaded to the Dashboard every 5-10 minutes, so some reports or recordings may not appear in the Dashboard right away.