I have noticed that about 90 or even 95% of nutriberries I serve are not getting eaten. Because I have lots of birds (10), and the birds have different preferences, and some are even being bullied when it comes to food, I always provide whatever possible all the time (at several locations)
Some of my tiels seemed to be pretty interested in Nutriberries earlier (mostly the babies), so I got a supply of them. The best result we had was when I was taking the flock out first thing in the morning while they are still in the cage after the night to ensure all of them go (to outdoor porch area). They were hungry and confined in a relatively small area of the porch, so I could see them eating Nutriberries more or less well (in a bowl on top of the cage). Recently, It's too cold to go outside in the morning. I take them out weather permitting, and not always succeeding (I have noticed that if they are not taken out in the morning, they won't go later even if I keep the front door open for a long time).
In the house, they don't eat nutriberries well for some reasons. Sometimes I can see a bird nibbling on them, but there is too much crazy flying that happens in the house (somebody's eating - the next second he is gone). More often I see that they prefer their seed mix (from the seed company) and sprouted seeds. They also get Pretty Bird pellets (and they seem to like them!) but I'd say that the overall amount consumed is very little. We also serve Roudybush pellets, same thing. Eaten a little bit.
I also noticed that quality of Nutriberries is rather inconsistent. I buy round tubes of classic Nutriberries at Amazon, and once I had a tube that was full of crumbled berries with the remaining berries being dried out (not the result of incorrect storage by me!). The second tube that came in the same parcel was OK. Anybody else seeing this?
I serve those berries in a shallow stainless steel cat saucer (diameter about 4 in) on the top of the cage. I would say the reduced interest isn't due to the way I serve them.
Any ideas, suggestions?

Oh, those finicky birds!
My tiels will eat nutriberries. However, they also really seem to like throwing them onto the floor. If I am feeding them in the cage, they will often try to push a nutriberry out through the bars so it falls onto the floor. I clean up many, many nutriberries on the floor and on the bottom of the cage.
For a while, I had Zupreem pellets. When I feed them in the dish in the cage, they won't touch them. Then, one day, I sprinkled some onto a large plate on top of the budgie cage, where there usually isn't any food. Suddenly, the tiels were eating them.
I have Roudybush pellets. Neither the tiels or the budgies are particularly interested in these.
All of my birds love the seed mix.
I try to restrict them to some form of pellet in the morning, then seed at bed time.
Yesterday, I caught one of the tiels trying to eat pellets out of the cat bowl. I immediately took it away, because I know cat saliva is very bad. Sigh.
I think putting food in unusual places, where they can "discover it" makes it more desirable. This doesn't work with my budgies, because they don't come out of the cage.
If I pound the nutriberries with a rolling pin, to break them up, the budgies will eat them. Otherwise, no. This is even though I buy the nutriberries that are labeled for budgies. Breaking up the Nutriberries is a lot of work. Sigh.

Diane thanks.
I usually smash some of them, and leave others intact so they have a choice. The problems are: berries fall out of the bowl and onto the floor as you said. Or, if not eaten quickly, they dry out.

I find that the Nutriberries are pretty dry already and I don't think there's much scope for them to dry out any further. But different batches vary in how hard they are, and I always assumed there was some variation in the stiffness of the "glue" that holds them together.

I mean soft and easy to eat VS hard as a rock.
If you leave them out exposed to air, they harden in a little bit.