Import Block throws was null but now cty error

I am in process of creating provider for a saas product using Framework plugin. The provider with a resource is working fine of Create, Read, Delete, Update and Import. But when i try using the same with Import Block it shows below error message consistently.

.subdomain: was null, but now cty.StringVal("url12345")
      - .username: was null, but now cty.StringVal("mailid")
      - .default: was null, but now cty.False
      - .domain: was null, but now cty.StringVal("domainname")
      - .domain_cname: was null, but now cty.ObjectVal(map[string]cty.Value{"data":cty.StringVal("domainname"), "host":cty.StringVal("url1234.domainname"), "types":cty.StringVal("cname"), "valid":cty.True})
      - .owner_cname: was null, but now cty.ObjectVal(map[string]cty.Value{"data":cty.StringVal("mydomainname"), "host":cty.StringVal("1234567.domainname"), "types":cty.StringVal("cname"), "valid":cty.True})
      - .legacy: was null, but now cty.False
      - .user_id: was null, but now cty.NumberIntVal(123456789)
      - .valid: was null, but now cty.True

Below is my schema.

func (r *linkbrandResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	resp.Schema = schema.Schema{
		Description: "Resource to manage link branding",
		Attributes: map[string]schema.Attribute{
			"id": schema.Int64Attribute{
				Description: "The ID of the link branding",
				Computed:    true,
				PlanModifiers: []planmodifier.Int64{
					int64planmodifier.UseStateForUnknown(),
				},
			},
			"user_id": schema.Int64Attribute{
				Description: "The ID of the user",
				Computed:    true,
				PlanModifiers: []planmodifier.Int64{
					int64planmodifier.UseStateForUnknown(),
				},
			},
			"domain": schema.StringAttribute{
				Description: "The domain name",
				Required:    true,
			},
			"subdomain": schema.StringAttribute{
				Description: "The subdomain name",
				Computed:    true,
				Optional:    true,
			},
			"username": schema.StringAttribute{
				Description: "The username",
				Computed:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
			},
			"default": schema.BoolAttribute{
				Description: "The default domain",
				Computed:    true,
				Optional:    true,
				Default:     booldefault.StaticBool(false),
				PlanModifiers: []planmodifier.Bool{
					boolplanmodifier.UseStateForUnknown(),
				},
			},
			"legacy": schema.BoolAttribute{
				Description: "The legacy domain",
				Computed:    true,
				PlanModifiers: []planmodifier.Bool{
					boolplanmodifier.UseStateForUnknown(),
				},
			},
			"valid": schema.BoolAttribute{
				Description: "The valid domain",
				Computed:    true,
				PlanModifiers: []planmodifier.Bool{
					boolplanmodifier.UseStateForUnknown(),
				},
			},

			"domain_cname": schema.SingleNestedAttribute{
				Computed: true,
				PlanModifiers: []planmodifier.Object{
					objectplanmodifier.UseStateForUnknown(),
				},
				Attributes: map[string]schema.Attribute{
					"valid": schema.BoolAttribute{
						Description: "The valid domain",
						Computed:    true,
						PlanModifiers: []planmodifier.Bool{
							boolplanmodifier.UseStateForUnknown(),
						},
					},
					"types": schema.StringAttribute{
						Description: "The type of domain",
						Computed:    true,
						PlanModifiers: []planmodifier.String{
							stringplanmodifier.UseStateForUnknown(),
						},
					},
					"host": schema.StringAttribute{
						Description: "The host of domain",
						Computed:    true,
						PlanModifiers: []planmodifier.String{
							stringplanmodifier.UseStateForUnknown(),
						},
					},
					"data": schema.StringAttribute{
						Description: "The data of domain",
						Computed:    true,
						PlanModifiers: []planmodifier.String{
							stringplanmodifier.UseStateForUnknown(),
						},
					},
				},
			},

			"owner_cname": schema.SingleNestedAttribute{
				Attributes: map[string]schema.Attribute{
					"valid": schema.BoolAttribute{
						Description: "The valid domain",
						Computed:    true,
						PlanModifiers: []planmodifier.Bool{
							boolplanmodifier.UseStateForUnknown(),
						},
					},
					"types": schema.StringAttribute{
						Description: "The type of domain",
						Computed:    true,
						PlanModifiers: []planmodifier.String{
							stringplanmodifier.UseStateForUnknown(),
						},
					},
					"host": schema.StringAttribute{
						Description: "The host of domain",
						Computed:    true,
						PlanModifiers: []planmodifier.String{
							stringplanmodifier.UseStateForUnknown(),
						},
					},
					"data": schema.StringAttribute{
						Description: "The data of domain",
						Computed:    true,
						PlanModifiers: []planmodifier.String{
							stringplanmodifier.UseStateForUnknown(),
						},
					},
				},
				Computed: true,
				PlanModifiers: []planmodifier.Object{
					objectplanmodifier.UseStateForUnknown(),
				},
			},
		},
	}
}

Happy to share more details if needed.