My TV doesn't support 4k resolution. It is usual 2k TV.Try setting the actual device display to 4K2K@60.
That is bad news (((. Actually, I tried to use AFRd application, and it became switching to 1080/24 automatically in Kodi, but it doesn't switch back to 1080/60 at all. So it doesn't work too. I didn't find a way to set it up correctly.The CE ROM unfortunately didn't work particularly well with AVR's either so other than to help beta test & test the final release of the CE FW I discontinued use & remained with the official 6.0.1 FW for my subjective needs.
The player became extremely slow after a time. Youtube can start a minute, then show a message that it doesnt respond. The same is for Neutron player. So I decided that there are two reasons: extremely old android version and low amount of memory. I cannot add/replace memory, but I can update firmware )))). So I tried it. Unfortunately AFR functionality doesn't work properly. It worked fine in the original firmware, so I didn't expect such an issue. And nobody reported this issue in this topic ..Is there any particular reason why it's absolutely essential for you to use the 7.1.2 CE ROM?