Filtering not working

Question

Hi guys, I hope everyone is doing well.

I am developing an app in PowerApps, it is connected with a SharePoint list.

At the beginning of the app (OnStart) I have this code:

Set(varMonth,Text(Now(),"mm"));
ClearCollect(colBirthDay,Sort(EmployeesDirectory,Mbirth,Ascending));

Then in a gallery I am trying to filter the collection records like this:

Filter(colBirthDay,Mbirth=varMonth)

But I can't get the gallery to be populated, but if I put only the collection name I got all the records.

I have verified the variable contains a correct value and if so, for example for this month the variable should be 04 and that is the value I got and I have records that meet that filter.

The field I'm filtering by is a single line of text field.

Do you have any idea why this behavior and why the gallery is not showing with the filtered records?

Thank you very much,