### **Environment**:

Your OpenProject Version: 12.0.1

### **Steps to reproduce:**

1. Create a work package custom field, tick 'Used as a filter'

2. Create a work package query using this custom field as a filter

3. Edit the custom field and uncheck 'Used as a filter'

4. Open the work package query and try to export as, say, XLS


Also broken in this scenario:

* The filter button shows e.g. (2) filters in the count badge, but only one is shown in the filter configuration list, so users cannot remove it

* "Save" and "Save as" don't work, errors are thrown in the console, but no error message appears on screen


### **Actual Behavior**

A red error message with "Bad request."

### **Expected Behavior**

The export Begin of the insertionworks, the invalid filter is ignored.End of the insertion Begin of the deletion should work.End of the deletion
The invalid filter field is omitted (not shown in the count badge or the filter list).
Saving Begin of the insertionand saving-asEnd of the insertion Begin of the deletion or saving asEnd of the deletion does work without throwing an exception in the console

<br>