I am experiencing an issue where WP All Import fails to save multiple selected items into a Meta Box post relationship field set up as a checkbox_list. When importing records with multiple values (e.g., multiple post slugs), only the first post item gets checked in the WordPress admin editor.
#### **Field Setup & JSON Schema**
* **Field Type:** post
* **Field Option:** field_type: "checkbox_list"
* **Target Post Type:** custom_post_type
{
"type": "post",
"id": "my_custom_post_relationship",
"name": "Related Items",
"field_type": "checkbox_list",
"post_type": [
"custom_post_type"
]
}
---
#### **The Problem**
1. In our CSV import file, rows with multiple relationships have delimited post slugs:
item-slug-1|item-slug-2|item-slug-3 (or clean comma-separated slugs: item-slug-1,item-slug-2,item-slug-3).
2. In **WP All Import**, we map the Meta Box field to {my_custom_post_relationship[1]} and specify | (or ,) as the delimiter.
3. **Result:** When the import completes, only the **first item** (Item 1) is checked in the Meta Box UI on the edit post screen. The subsequent items (Item 2, Item 3) remain unchecked.
---
#### **What We Have Tested**
* **Manual Updates:** If we manually check multiple boxes inside the WordPress editor and click **Update**, Meta Box correctly saves and displays all checked items in the database. The issue occurs specifically during the automated import pass with WP All Import.
* **Delimiter Formatting:** We have tested pipe-separated strings (slug-1|slug-2), comma-separated strings without spaces (slug-1,slug-2), and post title values (Item Title 1, Item Title 2). In all cases, WP All Import only populates the first matched item into Meta Box.
* **WP All Import Mapping:** Matching mode is set to **Post Slugs**.
---
#### **Questions**
1. What is the exact string or delimiter format that the **Meta Box WP All Import Add-On** expects in a CSV cell for a post field with checkbox_list enabled to ensure all IDs or slugs are saved simultaneously?
2. Does Meta Box expect WP All Import to write multiple meta rows with the same key (my_custom_post_relationship), or a single serialized meta entry, and is there a specific filter/hook required to ensure all array items pass through during import?
Thanks in advance for your help!
.
