I understand that Smart Sync and Time Machine don't play well together, and I more or less understand why (as a side note, this strikes me as a big issue for the Dropbox folks, which they need to figure out some way to address; Time Machine is an important Mac application, and people need to be able to use it).
Having learned about this problem, I'm trying to move back to Selective Sync rather than Smart Sync. I have a couple of questions:
1. How do I turn off Smart Sync? Is it as simple as just asking for some folders to be selectively synced? There doesn't appear to be a "don't use Smart Sync" option.
2. How can I find all folders and files that are smart synced? Is there a better/easier way than scanning the file list looking for tiny non-green icons?
As for Smart Sync, there isn't a direct way that you could see which files are Smart Synced (like an exported list of online-only files). However, you can tell from the sync icons as they appear on the desktop app and File Explorer/Finder.
For example, if a path has an online-only file, the folder will have a mixed state with a white icon with a green tick.
If you don't want to use Smart Sync, you can opt out of the system extension by following the steps shown here.
Thanks. I will just note, however, that Time Machine *is not* a third-party backup app. It is an integral part of MacOS, and if Dropbox continues to fail to support it, that seems like a bad business decision.
Just to be clear. I'm not simply pointing out that it's not an ideal situation. Millions of people use MacOS, and most of them use Time Machine. If you don't properly support Time Machine, it's hard to see how you can say you support MacOS. Don't get me wrong, I will continue to use Dropbox, at least for the present, but this really seems like a pretty big hole in your application.