Anaplan features mapping/ETL support for imported data. Without knowing the specifics of your file format I've mocked up a simple example.
Using a basic txt file for import with the date format in question. In this case row 1 is the header row. Data starts at row 2.
Now with the module open to the data grid view import the file.
Import mapping windows will open. Make sure Header row and first data row are correct as well as separater. Anaplan is very good about pre-determining the incoming format but its always good to verify.
Hit next to map the data.
Lets focus on time and assuming that all other columns map correctly.
Anaplan has the ability to map various date formats to the anaplan format.
Now map the Source to Target on the Mapping tab and then go to the Time tab.
See illustration below.
Go ahead and map the rest of the columns and load the data. You may need to try this a few different ways demanding on the source data format.
Hopefully this provides a few idea on loading data files that contain dates.
Was the module you were entering the data dimensionalized by time? And if so, what was the granularity of Time (day, month, etc)? If you did have the module my month, but the data in the file was at the day level, Anaplan will automatically sum the data up to the granularity of the target (again, I am assuming at the month level).
Ok, let's try this...I have attempted to recreate exactly what you have, but if not, please correct me.
I have uploaded a csv file which looks likes:
Notice, the date is rendered as YY-MMM, but you have to remember this is only a renderning and now exactly how the date is being stored in the file. If you click within the cell fo a a date, you will see date is actually a true mm/dd/yyyy date. This might be where your issue is, but I am not sure.
When I upload that file to Anaplan, please make sure your headers data rows are defined correctly. Also, for the time being, please make the Defualt file permissions to Everyone. This can be changed later, but for testing purposes, set it to Everyone. Also, on the left side, make sure your Column Separators are correct.
In the Mapping, please make sure you map the correct columns to the data. For Time, notice Anaplan is "seeing" the data as YYYY-MM even though the representation is different (YY-MMM).
On the Time tab, make sure mapping is similiar to the below:
The Currency Tab should look like:
And the Line Item tab should look like:
When your run the action, you should get all green checks