[Resolved] ACF Flexible Content Translations Become Misaligned or Disappear After Adding/Removing Blocks

Thanks for getting back to me,

What's likely happening: flexible content rows are stored as an indexed set of meta keys (field_name_0_subfield, field_name_1_subfield, etc.), with the layout name at each index defining "which row is which." When a new block is added in English, every row after the insertion point shifts index. When an empty row is deleted, that index disappears entirely. That part of the behavior is standard ACF flexible content storage and is consistent regardless of language setup.

How ACFML then syncs or maps translated content against those indexes isn't something we're able to speak to. ACFML is developed and maintained by the WPML team, not by ACF, so we don't have visibility into how it tracks rows across translations or why an index shift would cause content to detach or reappear the way you're describing. That logic lives entirely on their side.

Since the behavior is tied to how ACFML handles syncing rather than anything in ACF's own data structure, the WPML/ACFML team would be best placed to confirm whether this is expected behavior, a known limitation, or something they'd class as a bug. They'll have the context on how their sync layer matches rows that we simply don't have access to.

Let us know if WPML support comes back needing anything on the ACF data structure side, happy to dig further if it turns out there's something we can help clarify.

I have updated all WPML-related plugins, ACF PRO, and all other plugins to their latest available versions, but the issue still persists.

I have also recorded a video demonstrating the issue step by step.

Test product:
hidden link

The issue is 100% reproducible by following these steps:

Open the English product.
In the ACF Flexible Content field, add a new layout between the existing blocks (not at the end).
Move the new layout to the desired position.
Update the product.
Open the German translation.
The existing German content becomes misaligned:
content from other blocks appears inside the newly added block;
content from existing blocks disappears or shifts to another block.
Go back to the English product and remove the newly added layout.
Update the English product again.
Open the German translation once more.

At this point, the German content returns to its original correct state.

This behavior is 100% reproducible on this product.

I have also checked my ACFML configuration:

Flexible Content = Copy
Text / WYSIWYG fields = Translate
Image / Relationship / True-False = Copy

I also exported the field group and verified that the translation preferences are configured correctly.

Since removing the newly added layout immediately restores the translated content, it appears that the issue is related to how ACFML synchronizes Flexible Content rows after inserting or reordering layouts, rather than to the field configuration itself.

From what I can observe, the issue seems to occur when inserting a new Flexible Content layout changes the row indexes. For example, a structure like:

builder_0
builder_1
builder_2
builder_3

becomes:

builder_0
builder_1_new
builder_2
builder_3
builder_4

It appears that the existing translated content is then mapped to the wrong rows. When the newly inserted layout is removed, the original row indexes are restored, and the translated content immediately becomes correct again. This makes me think the issue is related to how translated Flexible Content rows are synchronized after row indexes change.

Could you please try reproducing the issue on the provided product while following the attached video?

I have already provided administrator access as well as the FTP credentials, so you should have everything needed to investigate the issue directly. If you need any additional information or if there is anything else I can do to help reproduce the problem, please let me know.

video: hidden link

Thank you.

Thank you for confirming that you were able to reproduce the issue on a clean installation and for escalating it to second-tier support.

I understand that the issue occurs with the Classic Translation Editor, while it does not occur with the Advanced Translation Editor. In my case, the translations are currently managed using the WordPress Native Editor.

I will wait for your further findings before making any changes to the translation workflow, as I want to avoid affecting the existing translated content.

Thank you.