With the Adobe Creative Cloud update to version CC 2018 available since 18.10.2018, Adobe&s support for the Dolby (Plus) audio format is no longer available in all CC programs - the Dolby Codec is no longer included in CC. Adobe refers to Dolby&s native (decoding) support by modern operating systems, which is included in Windows from version 8.1 and Mac OS X. 11. Users of older operating systems are advised to upgrade to the latest version of Adobe to play Dolby (Plus) audio files.
If you want to encode Dolby, you have to use either an external, paid solution like SurCode or the Dolby Media Producer Suite - or use a previous version of Adobe CC Premiere or Media Encoder for Dolby Encoding. To do this, the checkbox "Delete previous version" in the advanced settings must be deactivated during the update.