Hi @James
ACF doesn’t use the standard WP form, so the ‘postmeta_form_limit’ shouldn’t be an issue (unless i’m missing something).
Your best bet is to check your server logs for any hints as to server failure during the save.
Like I said, The max_vars is a good place to start, but it is important to make sure that this value is being used by your server. Please google how to test server info such as max_vars.
Good luck
Thanks
E
