App freezes

I have an object like map[uint64]map[uint64]Users, which I convert to ristretto cache model, I use map[uint64]Users as cache value.
The issue is I want to go through all map values to find required User struct, but I cant - app freezes each time I try to range over map. So, ristretto`s Get() returns a map[uint64]Users, but I cant traverse it.
I tried to print the value of map and it looks fine.
Its like this:
users, err := ristrettoCache.Get(userID)
if err != nil {return err}
log.Println(users) //stored value prints in terminal
if u, ok := users.(model.Users); ok {
log.Println(u.(model.Users).[1]) //also fine, it is printed in the terminal
for k,v := range u { // but app freezes trying to range