Dynamic lookup filter on Freedom UI

Hi,

I've created a custom FreedomUI page for AccountAddress object. I'd like to implement some kind of automation for two lookup fields: Country and Region. It consists of two parts:

1. When I choose a region from list, the country should be set to region's country. For example, if I choose Texas region, I expect that country will be set to United States

2. When I choose a country, regions lookup should display only these regions, which are connected with selected country.

I haven't any problem with implementation of the first part. But the second part doesn't work I expected. I use handler for crt.LoadDataRequest to append a filter parameter when loading regions list. The problem is that this handler runs only once, at first list load. It doesn't execute when I change country, although I trigger such request from other handler (crt.HandleViewModelAttributeChangeRequest). Here is the crucial of my code:

{
	request: 'crt.LoadDataRequest',
	handler: async (request, next) => {
        if (request.dataSourceName === 'Region_List_DS') {
	        const predefinedFilter = await request.$context.Region_filter;
	        request.parameters.push({
		        type: "filter",
		        value: predefinedFilter
	        });
        }
 
		return await next?.handle(request);
	}
},
{
	request: 'crt.HandleViewModelAttributeChangeRequest',
	handler: async (request, next) => {
        if (request.attributeName === 'EvCountry' && request.value?.value != null && (request.oldValue?.value == null || request.value.value !== request.oldValue.value)) {
			const countryId = request.value?.value;
            request.$context.EvRegion_filter = {
				"items": {
					"1954b2e1-ea91-4014-b785-cda17020595c": {
						"items": {
							"CustomFilters": {
								"items": {
									"customFilterCountry_Region_1664cb4d-2690-48d6-bcdf-0c8075824efa": {
										"filterType": 1,
										"comparisonType": 3,
										"isEnabled": true,
										"trimDateTimeParameterToDate": false,
										"leftExpression": {
											"expressionType": 0,
											"columnPath": "Country"
										},
										"rightExpression": {
											"expressionType": 2,
											"parameter": {
												"dataValueType": 10,
												"value": countryId
											}
										}
									}
								},
								"logicalOperation": 0,
								"isEnabled": true,
								"filterType": 6
							}
						},
						"logicalOperation": 0,
						"isEnabled": true,
						"filterType": 6
					}
				},
				"logicalOperation": 0,
				"isEnabled": true,
				"filterType": 6
			};
 
			const handlerChain = sdk.HandlerChainService.instance;
			const result = await handlerChain.process({
				type: "crt.LoadDataRequest",
				$context: request.$context,
				config: {
					loadType: "load"
				},
				dataSourceName: "EvRegion_List_DS",
			});
		}
 
		return next?.handle(request);
	}
}

The problem is that my trigger (handlerChain.process call) doesn't run crt.LoadDataRequest, and result variable contains full, unfiltered list of regions.