If there are a lot of assets in an asset manager folder and an admin changes the download restrictions (e.g. from "Inherited" to "Restricted" with a condition), then a time out occurs if there are a lot of assets in that folder. It takes longer than 50 seconds (which is the timeout I configured). I guess this is related to the permission syncing which checks every asset in that folder.
It might be good to evaluate if this can be improved in performance.