Lookup Column Search by Typing not work

I have a SharePoint list with one lookup column. Using standard new form, i can type some key word in lookup column, SharePoint will show me the value, which match the keyword. e.g. one Value in Lookup Column is "01 - Marketing". If I type "mar", this value will displayed. 

Now I make some customzing via Power Apps for list new form. After that, search in Lookup column does not work like before. I must type "01" to let it show matched value. Typing "mar" return empty. Has anybody idea to solve this problem?