Thank you for contacting us with this issue.
I kindly ask you to check if the validation rules are present in the related to the object xml file - you can easily navigate to an xml file using the 'Open in editor' command from the context menu of the object in the Admin Panel or from the toolbar.
If validation rules are absent in the xml file, please open the Project Metadata Components (from the menu Project) and disable the Object Metadata type, click 'Apply' - after this, objects will be removed from your TWS project. Then, please open the Project MetadataComponentsx wizard again, enable Objects, click 'Apply', and pull from Salesforce. This way the IDE will download your Objects again with the refreshed data. Then please refresh data in the Admin Panel and check if the validation rules will be present for your object.
If this won't help, please send us a bug report directly from TWS - you can find this functionality in the menu Help -> Report a Bug, please put your email and enable the 'Attach Log File' checkbox. This way we will receive your TWS log files that could help us to find a reason for the issue.
Is it reproduced for all your Objects or for some/one of them?
Looking forward to your response.