Vuejs update a value used with v-for dynamically - vue.js

Question

So I'm making an attendance tracker with Vuejs and Vuetify, and I want it to look like this:
A Calender made up of v-card components, and a list of absences read in from a database. I have my API set up and am able to retrieve a list of absences without any issues, but when it comes to putting them on the screen I have some issues. What I want to do is this:
The user selects the month and year. Each card then shows one day of this month. I have a function called getAbsDate(date) that returns a list of absences for the date passed to it. I want it to work something like this in each card:
<v-card min-height="170" tile>
<v-card-text class="text-center black--text">
{{i}}
<v-sheet
color="blue"
class="pa-1"
v-for="abs in getAbsDate(i+'.'+monthsNums[selMonth]+'.'+selYear)"
:key="abs['id']"
>{{abs["name"]}}</v-sheet>
</v-card-text>
</v-card>
selMonth is the month the user selected, and selYear is the year the user selected. This doesn't work however. I don't get any errors, the cards are just empty. getAbsDate() returns a list of objects. Any ideas as to why this doesn't work?
Thanks!
EDIT
Here is the declaration of my getAbsDate() function.
getAbsDate: function(date) {
let l = [];
this.absences.forEach(abs => {
if (abs["start"] == date) {
l.push(abs);
}
if (abs["end"] == date) {
l.push(abs);
}
let day_start = moment(abs["start"].replace(".", "/"), "DD/MM/YYYY")
.toDate()
.getTime();
let day_end = moment(abs["end"].replace(".", "/"), "DD/MM/YYYY")
.toDate()
.getTime();
let day_date = moment(date.replace(".", "/"), "DD/MM/YYYY")
.toDate()
.getTime();
if (day_start <= day_date && day_date <= day_end) {
l.push(abs);
}
});
return l;
}
}
The formatting is not quite right at the .toDate() and the .getTime(), but in my file it is, s it is not the issue.