Can not close NbDialog window on click outside of the modal window

### Issue type

**I'm submitting a ...**

* [x] bug report
* [ ] feature request

### Issue description

**Current behavior:**

I have a modal window and using NbDialog for this purpose.
And I noticed that if I have redirect to the several nested pages i,e /pages/page1/subPage2,
and open a modal window that can be opened globaly from the any page (it is in header of the site)., then
I can not close it on clicking outside of the window. I have to click 2 or 3 times in a row.

**Expected behavior:**

The window should be closed immediately after clickin outside the modal window.

**Steps to reproduce:**

**Related code:**

I use dialogService as in the example below:
```
this._dialogService.open(AboutComponent, {
context: {},
autoFocus: false,
});
```
In module.ts I have the following code:
```
const NB_MODULES = [
NbLayoutModule,
NbMenuModule,
NbUserModule,
NbActionsModule,
NbSearchModule,
NbSidebarModule,
NbContextMenuModule,
NbSecurityModule,
NbButtonModule,
NbSelectModule,
NbIconModule,
NbCardModule,
NbDialogModule.forRoot(),
NbPopoverModule,
NbInputModule,
NbCheckboxModule,
NbTooltipModule,
NbEvaIconsModule,
];

@NgModule({
imports: [SharedModule, CommonModule, ReactiveFormsModule, ...NB_MODULES],
exports: [CommonModule, ...PIPES, ...COMPONENTS],
declarations: [...COMPONENTS, ...PIPES, AboutComponent],
entryComponents: [AboutComponent]
})
export class ThemeModule {
static forRoot(): ModuleWithProviders {
return {
ngModule: ThemeModule,
providers: [
...NbThemeModule.forRoot(
{
name: 'default',
},
[DEFAULT_THEME, COSMIC_THEME, CORPORATE_THEME, DARK_THEME],
).providers,
],
};
}
}

```

### Other information:

**npm, node, OS, Browser**
```

```

**Angular, Nebular**
```

Angular: 9.1.12
Nebular: 5.1.0
```