Was this a major update (change of Android version) or just a security patch or similar? And are you talking about Android/data on a removable SD card or internal storage?
The purpose of the Android/data folder was to allow apps to store their private data when this might be too large for internal storage (normally app's private data live in /data/data/<package_name>, where you cannot see them without root). So there would be an Android/data folder on a removable SD card. Of course not all devices have removable cards, or may have the slot but be used without one, so you'll also get an Android/data folder in the shared internal storage (which, confusingly, can be addressed as /sdcard!). So my phone, which has no SD slot, only has an Android/data folder in internal shared storage (/storage/emulated/0, aka /sdcard), while my tablet has Android/data folders in both internal storage and SD card (with more subfolders on the SD card). This is one reason why I ask where you are looking, internal or removable storage.
But let's go back to the first sentence of the previous paragraph. The purpose of these folders is that the data are supposed to be for that app only. Obviously if they are on a removable SD card, whole filesystem doesn't support access control, this isn't going to work (so no sensible developer would put anything genuinely sensitive there, since any app could read it). But internal storage uses the ext4 filesystem which does support this, so it's perfectly possible to limit the apps that can see the contents of stuff stored there. And given the purpose of this folder it would make sense to do so (though actually it doesn't really make sense to have this folder in the shared internal storage in the first place: I assume they do that just for compatibility between apps that use this and devices that don't have an SD card in them). So it may be that what's happened is that as time has gone on Google have tightened up the security here, particularly if you are using Android/data in the internal storage. The only evidence I have to support that is that I can view the contents of this folder (even the internal version) on my tablet, which runs 5.1, but not on my phone which runs 11 (and I know I couldn't on 10 either, can't remember about 8 or 9). But this is why I wondered whether this might have been a major Android update.
If that is the case then it may be that your only solution is to explicitly download the files (which is another option in Dropbox). Arguably that is the way it's intended to work: "make available offline" means "make available in the Dropbox app when you are offline", it's not really supposed to mean "make available to any app". If the latter were intended then Android/data/com.dropbox.android would be the wrong place to store them, since Android/data is supposed to be for private app data. But if you do have an SD card then maybe see whether there's an Android/data/com.dropbox.android folder there too, since weaker SD card security may mean that you can see them there (if dropbox cached them there).
