I'm running the most recent install of TV on two devices both running the most recent version of Mac OS X Mojave Beta. After install and logging in, I set all permission to "Full Access" to be able to remotely control either of the devices, and both are set to have unnattended access as well.
When trying to run and contro the other computer, I am able to see the others Mac desktop screen, but cannot control anything at all, only see the screen. This is the same on both computers, neither being able to control one another.
I have the same problem on eight iMacs adn a Macbook that I upgraded to Mojave. TV 13 (full version) works fine as long as the display is awake. If the display goes to sleep (based on setting in System Preference -> Energy Saver), I can connect with Remote Desktop, and see the client's display screen, but keyboard and mouse actions are not accepted by the remote client. I do not have this problem with Macs running High Sierra.
You can try to connect, then when you see the black screen disconnect, and then reconnect, now the monitor should have turned on and you can control your device successfully.