Regrettably, it was found that in the update version 2600.4, a bug is present which disables Dolby Digital audio tracks. The TVs currently only function in PCM. The bug has already been reported to our R&D department. We don't know when a new update will be available. We expect that it will be soon.
There are some updates that are "forcibly" installed. This is especially necessary because of the apps in Smart Hub, which otherwise may stop working sooner or later. However there is a drawback when such a forced update also introduces bugs. For this situation, I want to take this opportunity to apologize.