I assume it flowers but perhaps the weather wasn't the best for the pollinating insects. if the flowers fail to form/open or get pollinated you wont get berries. I understand the flowers are green and not that obvious.

I had this problem with my butternut squash. The flowers are either male or female though both grow on the same vine yet they bloomed at different times and the female flower had to be pollinated 10 times by some bee to complete the pollination process. The flowers only opened for 1 day. No wonder I never got any squash. It's better to have more than 1 vine for cross pollination

I resorted to hand pollination. When the male flowers opened, I would snip it off and store it in the refrigerator in a ziploc baggie. When the female flowers opened, I would hand pollinate. I had to get up very early in the morning to do it when the blossom is fresh. I got 8 decent butternut squash last season and the raccoons stole 3. Still 5 is pretty good. That's an idea - hand pollinate.

It could also be weather related or maybe it just didn't have any viable female blossoms this year. Was the vine pruned? It could be under some kind of stress?

This plants has both male and female parts in the same flower and from what I can find you don't need to grow more than one to get berries.
It also dies back in the autumn so pruning the dead stems down wont affect flowers next season. Does yours do this Linmar?
Though some reports say it needs to have a warm summer to encourage berry set.

They do have separate male and female flowers and yes, having another vine will increase chances of pollination and berries because when one plant has only female flowers open, the other plant may have a few male flowers open and the busy bees will see to it. Here's what I found...

The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Insects.

https://pfaf.org/user/Plant.aspx?LatinName=Ampelopsis+brevipedunculata

However I'm not sure if this apples to each and every cultivar but this is for the species. When plants are hybridized often certain traits and characteristics are lost or compromised.

I've had this plant for several years, but only noticed the berries the last four or five years. Perhaps it needs to be mature enough to carry them?

Also the berries are highly favored by birds and wildlife so maybe the berries were gobbled up before you even knew they were there - like with my viburnums.