Once I get to 6 active downloads I can continue to save additional items to be downloaded, which are sent to the download queue as usual. However, in the last month or so these queued items refuse to download when the active downloads drop below 6. They stay permanently queued until I close out of the firefox session. When I reopen a new session these formerly queued downloads commence downloading without any action from me.

Any ideas how to get things back the way they were, where queued downloads would start to download as soon as the previous active download finished?