Pixmeister on "[Plugin: Polylang] include/exclude sync of AFC Repeater Fields"

Hi all
i use polylang ( great plugin :-) ) with Advanced Custom Fields.
The syncing of the custom fields works perfect and as excepted. (if i toggle customfield syncing in the polylang settings on/off).

Now i was looking for a way to choose wich custom fields should be synced and wich shouldn't. When i turn custom field sync to off and add this Filter to functions.php. A single Field is synced.

add_filter('pll_copy_post_metas', 'copy_post_metas');
function copy_post_metas($metas) {
      return array_merge($metas, array('single field'));
}

So far so good. Now, if i want to sync a custom field wich is based on
an ACF Repeater (i.e. my Gallery), the above code seems not to work.

I also tried the other way, by enabling custom field sync in polylang settings. (works with the ACF Repeater Gallery) and adding a code wich i found here, to remove the syncing of a field.

add_filter('pll_copy_post_metas', 'copy_post_metas');
function copy_post_metas($metas) {
      return array_splice($metas, array('my_slider_caption'));
}

That don't work and i get following error while Saving a page:

Warning: array_splice() expects parameter 2 to be long, array given in .../functions.php on line 134
Warning: array_unique() expects parameter 1 to be array, null given in .../admin-sync.php on line 124
Warning: Invalid argument supplied for foreach() in .../admin-sync.php on line 127
Warning: array_splice() expects parameter 2 to be long, array given in .../functions.php on line 134
Warning: array_unique() expects parameter 1 to be array, null given in .../admin-sync.php on line 124
Warning: Invalid argument supplied for foreach() in .../admin-sync.php on line 127
Warning: Cannot modify header information - headers already sent by (output started at .../functions.php:134) in .../post.php on line 233
Warning: Cannot modify header information - headers already sent by (output started at .../functions.php:134) in .../wp-includes/pluggable.php on line 1179

Is there a way to add sync of the acf repeater field by code?
or is there a way to exclude certain custom fields from syncing?

Thanks in Advice!
Pixmeister

https://wordpress.org/plugins/polylang/