Hi and welcome to Arturia forums.
If your presets actually are in your preset folder, then i suggest you try to delete the db.db3 file in the main preset folder, and the open an application. Create a back up first, just in case.
If your presets are not in your preset folder, then please contact Arturia support, and perhaps download and install the previous version of Analog Lab.
There are more posts in Analog Lab 4 and V-Collection forums about this issue. You can find and read them too for further informations, if needed.