Mix and Match discount: Deal price discount type does not work

Dear All,

I did setup a Mix and Match discount as screen shot below:

I selected "Deal Price" for the promotion items, but this doesn't work in POS. I did select these two items, but the price of Promotion item (green line) was not changed, still $2.7 instead of $1 as I setup.
System will work well if I select both are Discount % as below:

Please let me know why "Deal Price" in Mix & Match discount doesn't work ? How can I fix this issue?

Thank you