Deploying my project to the cloud causes a red exclamation mark in the deployment package repository, without further information. This appears to be caused by the IMAP_POP3_email module that (for migration purposes) temporarily was renamed in the project. Conclusion: the red exclamation mark can be caused by the rename of a module in your project.
Simple renaming also does the job
Try reimporting the widget and update all widgets, this sometimes solves it for me in similar circumstances.