Project Workbench not opening properly
This is happening due to the "Project Workbench" UI Action being customized.
Once this is reverted to Out of the Box, everything works as expected.
To do so, follow the steps below.
1. Navigate to System UI > UI Actions
2. In the "Name" column search for "Project Workbench" and go to the record
3. In the Versions related list, Right-Click the latest record with the Source of "System Upgrades: glide-VERSION..."
4. Select "Revert to this version"
5. Select OK when prompted