Same happens to me. I have a 1 year old Sony OLED and a Yamaha A6A. Have unplugged and reconnected a few times but still same delay.
Good to learn this also happens with a different brand TV. It should be noted this issue also occurs when streaming a series on Netflix and there is an automatic transition to the next episode. There is no sound from the AVR for about 10 seconds after the next episode starts playing, presumably because the ARC stream was interrupted while the next episode was being buffered. Hopefully, this is not a hardware issue and it can be corrected in a future firmware update. (Note to
@clone1008 : this operator has a master's in electronics engineering and 35+ years of experience in analog/digital hardware and software development, so hardly "faulty." Regarding the assembly of the mic and stand, if I wanted a time-wasting puzzle without instructions, I would buy a piece of cheap Ikea furniture, not a $2,200 AVR.)
I believe I have identified the source of a different sound reproduction in the "2ch Stereo" and "Pure Direct" modes. In the Speaker > Parametric EQ section of the settings, the YPAO has set "corrections" to the frequency response of all speakers and automatically selected the "YPAO:Flat" setting which, according to the User Guide "Adjusts each speaker to achieve the same characteristics." In my case, YPAO emphasized the 157.5Hz while deemphasizing the ~32Hz and high-frequency bands, which is exactly what I perceived. Since may front speakers are factory-tuned to within +/-0.5dB from the reference, and are said to be +/-1.75dB flat from 50Hz to 20kHz, I chose the YPAO:Front instead, but I may ultimately choose the "Through" mode that does not use the equalizer at all. I have serious doubts about this little consumer electronics mic accurately measuring the FR. Also, on that "correction" screen, bands do not appear sorted by rising frequency, which makes the interpretation more difficult.