SQLServer Khmer language empty check fails

When trying to compare unicode text with empty string, only Khmer language fails. Below is what I'm trying to do:

    create table #temp(data_value nvarchar(100))

    --Mandarin Language
    insert into #temp(data_value)
    select N'万世巨星'

    --Empty string
    insert into #temp(data_value)
    select N''

    --Khmer Language
    insert into #temp(data_value)
    select N'កុងហ៊្វូផេនដា ៣'

    select * from #temp

    --BELOW is fine/correct
    select * from #temp
    where data_value is null

    --BELOW check fails for Khmer language only
    select * from #temp
    where data_value =''

    drop table #temp