Can’t help from Homeseer perspective, but the EZIOxx family of devices require an Input to be LINKed to something before an Insteon command is issued when the Input changes state. It is the “Controller of” Link record in the EZIOxx link database that tells the EXIOxx where to direct the Insteon Group Cleanup ON/OFF message when the Input changes state. Some HA software periodically queries devices to determine the current state, don’t know if Homeseer has that capability or how useful that would be. Depends on how quickly you need to know when the Input changes state.
The need to be LINKed is not unique to EZIOxx devices. The Smarthome Keypadlinc, for example, with its 6 or 8 buttons, pressing button 3 does not cause an Insteon command to be issued unless button 3 is LINKed to something. As with the EZIOxx, it is the “Controller of” link database entry in the Keypadlinc that tells the Keypadlinc where to send the Group Cleanup ON/OFF commands.
EDIT: There is a feature of the EZIOxx devices that permits a broadcast message when the input is not linked. From the EZIOxx Command Set document…
Broadcast on Status Change: when the input is not linked, a broadcast message is sent with the input status encoded.
EDIT2: Tested with an EZIO2X4 (inputs are like an EZIO8SA, just not as many). Turning on the “Broadcast on Status Change” option, when an Input state change occurred, a Broadcast message is sent, Status Change command 0x27 in cmd1, bit pattern in cmd2 reflects the current state of each of the Inputs.
Don’t know if Homeseer supports this option.