Separate from the custom access URL, PMS v1.42.1.10060 has a bug that can cause downloads and optimizations to stay queued.
If Settings → Transcoder → Maximum simultaneous background video transcode = Unlimited, then any downloads or optimizations that need transcoding will stay queued, and not be processed.
The workaround is to change the setting to anything but Unlimited.
The bug is fixed in 1.42.2.10102.
