I have been trying to deploy apex classes to a Trailhead Playgound as well as a developer org, but I receive the error "SFDX: Deploy Source to Org failed to run" in VS Code. 

Did I miss something when I set-up VS Code?

• Salesforce CLI is up to date
• All extensions are up to date
• The orgs in question have been authorized successfully
• The CLI appears to be installed correctly (when I run "sfdx" in the Terminal, I receive the Salesforce CLI menu)

This is the Salesforce CLI output:
Starting SFDX: Deploy Source to Org
11:35:46.868 sfdx force:source:deploy --sourcepath c:\Salesforce\VSCodeQuickStart\force-app --json --loglevel fatal
11:35:48.630 sfdx force:source:deploy --sourcepath c:\Salesforce\VSCodeQuickStart\force-app --json --loglevel fatal ended with exit code 1

Any help would be much appreciated!

I am getting the following error (repeated for multi objects) during deployment from Sandbox to Sandbox (We are deploying using Ant).:

Error: workflows/Account.workflow(414,12):This workflow rule currently has pending actions in the workflow queue. To delete, please remove those pending actions.

The thing is that those pending actions were deleted a week ago, from both environments, the first time this came up. And I also deleted the workflows from my Eclipse project, deployed succesfully, and then re-added them to the project to make sure there was nothing in Eclipse that was the issue. Definitiely seems like the "Sending" Sandbox is "remembering" that there used to be pending actions.

Any suggestions on what I can do to clear this old information out?