The fix for the watermarking issues is now being deployed. There may be some short delays in generating previews as the transcoding images are updated..
Posted Nov 15, 2017 - 23:58 AEDT
We have identified an issue with the media watermarking feature that causes preview tasks to become 'stuck' generating previews. We're working on a fix and hope to have it live within the next 12 hours.
The temporary work-around is to disable the watermarking feature until the issue is resolved.
The issue was introduced as a result of a security update.