EI: Custom field drop-down single select does not sync to EI when an option is removed in Details Panel Settings

Issue Summary

Custom field drop-down single select does not sync to EI when an option is removed in Details Panel Settings.

Steps to Reproduce

1. Create a custom field drop-down (single select) with a few options in Administration → Details Panel Settings
2. Go to the correct work item and select option 2+ (not the first one since we can't delete it), save
3. Remove the selected option in Details Panel Settings
4. Refresh the work item page and see that it has no option selected
   1. API correctly returns null for that custom field
5. Observe EI Custom Dropdown field does not update to NULL

Expected Results

NULL value should be synced to EI, the same as when updating the field manually to 'Select One' non-option.

Actual Results

EI shows the previous dropdown value which is now invalid.

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available.

When removing a custom field option in Details Panel Settings, make sure to check which items could be affected by it and manually change their selection to the correct one.