text.replace is not a function error when use [ngOptionHighlight]="search"

I am using ng-select with dynamic items (load items from API). Items, which I receive is just an array of objects that have only 3 properties: Id, Name, Group. BindValue and BindLabel set to Name property. Name contains values in Russian language

This is the code, which I use to ng-select dropdown list:

<ng-select [items]="fastSearchResult"
        [multiple]="true" [(ngModel)]="fastSearchObj.search" (search)='fastSearchChanged($event)'
        groupBy="group" bindLabel="Name" bindValue="Name"
        class="form-control keyword"
        placeholder="Быстрый поиск вуза, спец-ти ">
    <ng-template ng-optgroup-tmp let-item="item">
          <div>{{ item.group }}</div>
     </ng-template>
      <ng-template ng-option-tmp let-item="item">
           <div [ngOptionHighlight]="search" class="fs-13 ml-1 lh-20">{{ item.Name }}</div>
       </ng-template>
</ng-select>

Be aware that I use Subjects to trigger a moment when a user stopped typing and send a request to API Each time when ng-select receives a result it shows an error:

text.replace is not a function at stripSpecialChars (ng-select.js:1056)

Inside of this function:

function stripSpecialChars(text) {
    /** @type {?} */
    var match = function (a) {
        return diacritics[a] || a;
    };
    return text.replace(/[^\u0000-\u007E]/g, match);
}

Could you please advise what i need to do to resolve the issue? Can the Russian language be a problem? It used to work in AngularJS

Many thanks

[Khokhlachov]

@Denis-Evseev your “group” in groupBy="group" is numbers and error in https://www.screencast.com/t/Jk3tJCk2 need map your “group” value to string

[ComsatArchitects]

To reproduce - have a ng-select that is not searchable, but type a letter anyway when it’s open.

I typed “d” and the first time through it called function stripSpecialChars(‘d’) on line 1064 of ng-select.js

The function ran again but for some reason it called stripSpecialChars(false) and it threw the error, not knowing how to deal with “false” as an input.