I recently filed a bug where dragging a sequence into a new timeline with the "Insert and overwrite sequences as nests or individual clips" option enabled would wipe out all transitions (not just audio), but I haven't seen this specific issue. These are user-to-user forums, so if you want the team to be aware of the issue you need to file a bug on UserVoice with as much detail as possible. Screen recordings showing this in action are the most helpful. If the team can't reproduce the issue then they won't know how to fix it. https://adobe-video.uservoice.com/forums/911233-premiere-pro
You can also check out the new Public Beta from the "Beta Apps" section of the Creative Cloud app. Builds of the public beta are released every day vs. the official releases which come out every month or so. It's possible this bug is already fixed in the beta. You can have both installed side-by-side and not cause any issues. You can even open projects in both apps and go back and forth. There is a new captions workflow in development, so if you were to enable that it would require the beta to change the project format to version 15 vs version 14, and you would not be able to open the same project in both versions. More info here: https://community.adobe.com/t5/premiere-pro-beta/discuss-new-captions-workflow-in-premiere-pro/td-p/...
But if you don't mess with the new captions workflow then you can go back and forth.
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