Data was clean after saving

[vvvhung]

Details

• WordPress version: 5.4.10
• ACF version: 5.8.3
• For UX/UI issues: [ OS, browser name and version ]
• Allow null: true
• Multiple values: true
• Stylised UI: false
• Condtional logic: false
• Rules: []

Reproduction

If you're filing a bug, please describe how to reproduce it. Include as much relevant information as possible, such as:

Bug summary

I add country field for an old group and go to the post to update data. After click update post, data disappears. I query postmeta table and find that data was clean for that post.

Steps to reproduce

1 - Go to an available custom field 2 - Add country field and save 3 - Go to the associated post and add countries for existing row and click update post

Actual result

Data on the post disappeared.

Expected result

Data remain.