Mine was already at 1080. I tried changing down to 720p. I tried different HDMI cables. I Tried different HDMI inputs on my TV. (BTW my TV is a RCA 48" LED Dont know the exact model but that should be new enough) Nope 17.6 works nice. Any suggestions for getting 18 to work so far has resulted in hard lockups when trying to stop a video or scroll backward or forward.
I've been playing with it recently. For me it seems to be hit and miss and mostly depend on what video I 1st watch after reboot. If I watch a blueray rip 1st, everything seems to play fine. If I watch a (non-HD) TV recording after reboot, I still (usually) get a freeze when exiting playback (even with the whitelist set properly). However, as I mentioned, once I've successfully started and exited a 1080p recording after reboot, it seems like anything else I play thereafter works fine. It may well be TV related (machine is still working after 'freeze', I can still ssh into it just display has stopped). As I virtually never reboot, I think the status-quo is sufficient for my needs, and playback seems improved compared to Krypton so far,