What kind of data contains the ApexSQL\ApexSQLAudit\Auditing\MSSQLSERVER\Packages folder and why it is now empty where previously was piled up with data? (4362217)

This means that all pending packages have been processed successfully.

In the “Packages” folder, packages are created from the session file, which are then sent to Central. That folder is empty in most cases because the sending is done quickly. Distributed packages are created in that folder and then they are immediately sent to Central.

When there are a bunch of packages in that folder, their processing is slow, and in the meantime, a new package is being made, and Central did not manage to process everything quickly.

The main cause for this is the lack of HDD/SSD space which is easily detected by investigating application log files. This is the reason why that folder got accumulated, but when HDD/SSD low-space issue is solved, all accumulated packages were managed to be sent to Central.