InDesign is not synchronizing liked files automatically anymore on Mac OS

We are an agency and have a lot of Indesign-Files. The folders where the liked files are, are set on "only online" per default because they are huge.
Until now, when opening the Indesign-File, Indesign automatically synchronised all the liked documents, so that they were available offline. (The status automatically changed from "online only" to "available offline").

We made some updates and this is not working anymore!
We are currently on MacOS Sequoia 15.3.1 (24D70), Dropbox v218.4.4348, and Indesign 20.1

Synchronising each file manually is not an option, because the liked files are almost always over 200 different pictures in more than different 100 different Sub-Folders. (And we can also not synchronise the whole folder, because there are a lot of other huge files that we do not need and would fill up way too much space.) We do not want to package the linked files all in one place, because the liked files should stay in their root folders, as they are used for a lot of different things and must be managed globally.

Until now it always worked! What happened, so that this does not work anymore? 
This is crucial for our company and was always an important reason why we chose to use Dropbox.
Is there no fix?