Select2 in adminlte 3.2 not honoring input group class

Question

I'm trying to use the select2 with an input group in AdminLTE v3.2.0, but the button is moved to the next line after the select2 control. Anyone has experienced this?

I noticed that the issue doesnt happen when i use this for all select in the page

$(".select2").select2({ theme: "bootstrap4" });

the later when i do this in the same page

$("#cusid").select2({
                    width:'100%', 
                    placeholder: "<?= lang('search_customer') ?>",
                    minimumInputLength: 2,
                    ajax: {
                        url:  "url",
                        dataType: 'json',
                        delay: 250,
                        data: function (params) {
                            var query = {
                                search: params.term,
                                type: 'public'
                            }
                            return query;
                        },
                        results: function (data) {
                            return {results: data};
                        },
                        processResults: function (data) {
                            
                            return {
                                results: data
                            };
                        },
                        cache: true
                    }
                });

then this happens