Couple of troubleshooting questions:
What software version are you running?
If it's only HDMI 3 that's complaining, what happens if you disconnect the PureLink from HDMI 3? Does the issue stop. What happens if the PureLink is connected to one of the other inputs and you connect a camera on HDMI 3? Does the issue follow the PureLink, or stay with HDMI 3?
Have you tried a new/different cable to connect the PureLink to the C90?
Are you using an HDBaseT Extender? If so, have you tried swapping that out for another one?
Wayne
--
Please remember to rate responses and to mark your question as answered if appropriate
Wayne
Please remember to mark helpful responses and to set your question as answered if appropriate.