I have been testing every single build since 7.0.2 and on every single build I have the same problem. I was expecting the issue to be fixed in LibreELEC 8.0.0 but the same issue is still there.
I am using Tvheadend as client and Tvheadend 4.2 as PVR backend. I have a Cubox-i4x4 running kernel version 3.14 of LibreELEC. On the 7.0.2 version (with kernel 3.14) live TV is perfect. Channels tune with little delay, picture is perfect, audio is perfect, deinterlacing is perfect. In the issues below I have the EXACT same hardware.
On LibreELEC 8.0.0 and all builds from 7.90.001 until 7.95.3, live TV is basically unusable. I started with clean installations so the issue is not with upgrading. I set up Tvheadend in the same way, all other settings for playback and system same as 7.0.2. Once I go to TV, I tune to any channel and channel plays after a bit of buffering (longer than 7.0.2 but reasonable). Then I switch to another channel and sometimes it switches ok with little delay. But once I try to switch again (second time) or even sometimes just switching the first time, the buffering starts, goes to 100% really slowly (10 seconds), nothing happens, buffering starts again to 100%, nothing happens, and so on. I have to stop playback. Then I try it again and same thing happens after maximum of two channel switches.
I played with audio settings, video settings, deinterlace settings, etc. but nothing helps. I want to mention that on Tvheadend side, there are no errors so the issue is with Kodi. Something changed drastically from 7.0.2 that makes watching live TV unusable on my Cubox. I am not sure if anyone else is having the same issue.
Addition to the simple tuning of channels, I have another major problem. That is the missing deinterlace settings of "Double rate (inverted)" which I need for many HD channels to deinterlace correctly. In 7.0.2 I have four deinterlace methods and the ones that work are "Double rate" and "Double rate (inverted)". In every version since 7.0.2, those are missing but they are replaced with "Bob", "Bob (half)", "IMX Advanced" and "Low Motion" or something like that. I know that "Bob" method is equal to "Double rate" but "Bob (inverted)" doesn't exist and I need it for proper live TV watching.
Those are my two main issues. I can post logs if anyone wants to see them but for that I have to switch SD cards and annoy my wife. For now, maybe someone can tell me what's wrong with information above.