Cannot Search Contact or Group Name with Numeric

In my WhatsApp’s group name and contact name. I have a lot of group name represent by teacher ID number ie 7089-8089. Similar to some contact derive from ID then name. I noticed this issue for quiet some time, which is I cannot search by number/numeric on the search bar, it will not return any result for example I type 708, it didn’t show 7080-7089

I am using WhatsApp on iOS. Anyone has similar issue?