RealmDB Full Text Search not finding records

Here’s my request (performed from both C# client and through Realm Studio):
content TEXT "prm 18"

content field of one of records looks like that: "18x48 18x48x80 white 18 x 48 80 prm 1848 15"

search request returns nothing.
I was trying to set the content field to prm 18 directly. Same result. It can’t be found.

If I request content TEXT "prm" it finds all the correct records.

This looks like a bug to me.