Just for test
Use analog audio to your tv and if is the same then it is M8R audio decoder fault or delay - this is not necessary a fault, can be slow response .
This is only half of problem
Now you should use Hdmi audio with downmix audio setting, so this way you exclude the tv decoder - but not the internal switch.
Try to compare the results...
This is not very simple like i write here . It will depend more by the audio codec from your movie, by the Hdmi communication protocol betwen your tv and M8R, it is very possible to see another sony tv set that works fine. This can vary from model to model from same brand and from brand to brand also. Even if two products are from same brand is is not necessary to use same codes in their fw.
It is premature to pronunce without a test... Even if those tests are handmade..;-)