Default tab in Enterprise + Missing reviews

# Label Studio Enterprise Bug Report

## Summary
Default tab in Label Studio Enterprise is not functioning correctly, showing "0/total tasks". A newly created tab partially works but doesn't display all previously reviewed tasks.

## Version
- Label Studio Enterprise Version: 1.13.2.dev0

## Steps to Reproduce
1. Open Label Studio Enterprise
2. Navigate to the default tab
3. Observe that it shows "0/total tasks"
4. Create a new tab
5. Notice that the new tab shows tasks, but some previously reviewed tasks are missing

## Expected Behavior
1. The default tab should display all tasks correctly
2. A newly created tab should show all tasks, including all previously reviewed ones

## Actual Behavior
1. The default tab shows "0/total tasks"
2. A new tab shows some tasks, but not all previously reviews tasks are visible (all tasks are available, but some reviews are not)

## Error Message
When attempting to use the default tab, the following error is displayed:
```
Runtime error
invalid input syntax for type double precision: ""
```

## Screenshots

## Additional Information
- The issue started occurring this week
- The system was working fine previously
- Some tasks were saved in a previous snapshot of the default tab
- When creating a new tab after the default tab stopped working, not all reviews are shown

## Possible Solution
The problem occurred because there was an "order by" clause on a column named "index" that contained empty strings. In previous versions, the "order by" functionality treated this column as a string and had no issues. However, due to a version update, this behavior was affected. The problem was solved by removing the problematic column from the selected columns and ordering by a different column instead.

## Impact
This issue is preventing annotators from accessing all tasks and is potentially causing loss or inaccessibility of previously reviewed data.