I have the identical issue.
My sources are video camera.
My output goes to a CYP HDBaseT Splitter 1x4. (1x HDMI Input, 1x HDMI Output, 3x
HDBaseT Output). The HDBaseT is used to send video to Epsom EB-2265U projectors.
The HDMI output is used to send send to LENKENG HDBaseT over TCP/IP for multiple TV displays around our campus.
When I connect the sources directly to the HDBaseT Splitter, projectors and TV work perfectly.
When I connect sources to ATEM Mini, the projectors do not work, but the TVs work perfectly. (If i connect a monitor to the ATEM Mini no problems.)
Could it be that the output of the ATEM Mini is not compatible with the projectors and that a scaler is required? I don't believe it is an HDBaseT or HDCP issue, as there is no issue when source directly connected.
Thanks for your assistance