I recently bought an LG 65EF950V and paired it with a Yamaha YSP2500 that had been working fine with a Panasonic plasma for ages. I got the same issues and after lots of head scratching came up with the following solution. The first thing i did was run through the calibration process again with the soundbar connected to the new tv. That on it's own didn't cure the sync issues, but it did cure the turning on and off problem. The next thing i did was to swap ALL the HDMI leads for HDMI 2 leads. I had been using my original leads which are HDMI 1. For whatever reason (because in my mind there shouldn't be any technical reason) this cured the problem completely. I only have a BD player and a skybox connected, so including the lead from the soundbar to the tv it was 3 leads.
Of course, if you are using Netflix from an App on the TV, you must use the ARC connection on the tv. The other thing worth checking is that you have all your tv's sound output set to the soundbar and that it and your soundbar are set to HDMI. Also if your tv has any sync options in the sound section, enable them.
Edit: If you do replace the HDMI leads, make shure that any you buy really are HDMI 2. I had a bit of a problem finding anywhere that actually told you what the specs were for the leads they were selling were. HDMI 1 leads have a 10.2 Gbps throughput, HDMI 2 has 18 Gbps throughput. Unless any retailer can confirm the throughput for any leads, don't buy them.
