I see multiple Cuffdiff runs in your history but they were deleted. Some completed (red because they failed), some were still queued (gray), some are executing (yellow - permanently delete to stop the job completely).
Many of the inputs have been deleted, but I can see at least one problem: The reference GTF dataset is formatted with Ensembl chromosome identifiers and the native reference genome used for mapping is based on the UCSC version of the build with a different chromosome identifier format. These must be a match.
The FAQ help here can be reviewed to help with understanding the how jobs are run within the history and data formatting including advice about how to resolve genome mismatch problems: https://galaxyproject.org/support/
And the Tutorials here can be reviewed for best practice workflows, including RNA-seq: https://galaxyproject.org/learn/
Thanks! Jen, Galaxy team