I have been having continued issues with compatibility with my Samsung Q9FN, my Denon x6400h and my Xbox One X & PS4 Pro.
1.) My x6400 Denon recieved an update that allows ALLM. With my Xbox One X connected to the receiver, the Xbox shows ALLM is selected and available. However, the TV will only show Game Mode On/OFF. It does not show or allows me to select "Auto" even though the new firmware for the Denon specifically details that this is now available. Further proof is that the Xbox One X shows in the settings menu that ALLM is selectable and is selected. If it was not available, it would be greyed out. I tried a factory reset on the TV and it still does not work.
2.) When using my Xbox One X via my receiver, whenever I go to play a video from one of the video apps., Mixer, Blu Ray App, as soon as the video begins to play, the screen goes black and the TV reports a "No Source" error. I have to power down all devices in order to get the screen to come back. But when attempting to play a video agian, the same issue "No Source". Gaming is fine, but it is an issue when using a video app.
3.) In an effort to eliminate some of the above 2 issues, I decided to connect my Xbox One X/PS4 Pro to the One Connect Box directly. While this resolved the "No Source" issue and the ALLM issue, I now have Audio Delay when sending the Audio feed to the receiver. I have tried to use the Samsungs TV's audio delay and this does not fix it. I tired using the audio delay on the receiver and this does not fix it. The only fix, is to change the audio formate on the Xbox/PS4 to 2 channel sound. I have a 7.1 set up and having to set my consoles to stereo 2-channel is not acceptable. It seems like having ALLM and Freesync is too much and it cannot handle it causing audio delay.
In short, there is something wrong with this set and there have been numerous reports of compatibility issues with Samsungs 2018 TV's and receivers from other users. With my receiver receiving a firmare to make ALLM work and the Xbox reporting it works, the TV is not recognizing it. Then in order to hopefully alleviate some of the issues, going direct connect to the One Connect box causes Audio delay.
This TV has been nothing but issues after issues and there should not be this many complaints about compatibility.