Dolby Digital export in 2018 Release?

Sorry for the difficulty! Try one of these suggestions if you've lost Dolby functionality:

1. Your simplest and best bet is to recover your CC 2017 apps as they were before you installed CC 2018. See if you can use Windows Restore to roll back the state of applications on your computer to before that time. On a Mac, you'd use Apple's Time Machine.

2. If you can't do that, then do you have a system backup or image from when you had CC 2017 installed, or perhaps it's installed on another machine? You could possibly use that backup together with the CC 2017 direct download links to get back to where you were before. At  a minimum, you'll need both the Premiere Pro and Adobe Media Encoder apps.

3. If neither of those strategies recover a working CC 2017 for you, then you could try moving forward with CC 2018. You could use a third-party utility like Handbrake (a free open-source video transcoder) to convert your MTS/ACS files. Rename the files and reimport them into Premiere Pro. Then clear your media cache.

4. If none of the above work, then maybe consider upgrading to Windows 10 while it's still free, and press ahead with CC 2018 (if you're concerned about Windows telemetry, that's easily handled). Meanwhile, for Mac users, macOS upgrades are always free... Windows 8.1 or above and macOS 10.11 or above contain native support for Dolby decoding functions. Again, rename the applicable files and reimport them on your new setup. Then clear your media cache.

5. If you can't upgrade your operating system, can't move forward with CC 2018, can't go back to CC 2017, and are genuinely stuck with a project caught in the middle – and none of the above solutions work for you – then you could try contacting Adobe Customer Care to let them know and see if they can help.

6. Moving forward, when upgrading Creative Cloud apps, use 'Advanced Options' in the Desktop app to retain older CC versions rather than the default behavior, which is to remove them.

Hope that helps!