Espresso ice cream problem

Hello! and thanks for having me in the club!
I thought I would inaugurate myself by posting a problem I'm having and see what you all think. I have a Cuisinart ICE-30BC Ice Cream maker, and I love it. But the other day, I made espresso butter almond ice cream from the recipe book that came with the machine. I let the machine run for like an hour and it never really thickened. The recipe said only 20-25 minutes but I was checking it all the time and it never got thick. I know you have to put it in the freezer afterwards to really have it settle, but this came out as liquidy as it went in. DO you think I beat the ingredients too much? and made it too frothy or something? I dunno. Any suggestions? Thank you for your help!

Here's the recipe:
Coffee Butter Almond Ice Cream
Ingredients
4 tablespoons unsalted butter
1 cup slivered almonds, roughly chopped
1 teaspoon kosher salt
1-1/2 cups whole milk, chilled
1-1/8 cups granulated sugar
3-5 tablespoons instant espresso powder (to taste)
3 cups heavy cream
2 teaspoons almond extract
1 teaspoon pure vanilla extract

Instructions
Melt the butter in a 10-inch skillet. Add the slivered almonds and kosher salt.
Cook over medium-low heat until almonds are toasted and golden, stirring frequently, about 4 to 5 minutes. Remove from the heat, strain (the butter will have an almond flavor; can be reserved for another use). Chill the nuts.
In a medium mixing bowl, use a hand mixer on low speed to combine the milk, granulated sugar and espresso powder until the sugar is dissolved, about 1 to 2 minutes. Stir in the heavy cream and extracts.
Turn the machine on; pour the mixture into freezer bowl, and let mix until thickened, about 20 to 25 minutes. Add the chopped nuts to the mixture during the last 5 minutes of freezing. The ice cream will have a soft, creamy texture. If a firmer consistency is desired, transfer the ice cream to an airtight container and place in freezer for about 2 hours. Remove from freezer about 15 minutes before serving.
For Coffee Ice Cream, omit the toasted buttered almonds, if desired; add 1 tablespoon Kahlua® or other coffee liqueur to the mixture. Kahlua® is a registered trademark owned by the Kahlua Company.