Hi Dylan, thanks for your reply.
I might have found a solution that works for me.
I now created the Athena table but specified the partition column as a string instead of an int (the values are not in the correct format to specify it as a date).
Then in QuickSight, after creating the dataset, I changed the partition column datatype in QuickSight to be a date.
QuickSight gave an error/warning that the value was not in a standard supported date format, but it gave me the option to specify the format, for which I entered YYYYMMDD.
This then appeared to work correctly- the values in the preview are correct and I was able to use the column in the settings for the incremental refresh.
I will do some more testing/verification on it.
(As a side note, when I tried to change the datatype in QuickSight to date back when the under lying Athena table has it set to int, the preview displayed the wrong date values so I guess it was assuming it was a unix timestamp or some thing.)
Thanks again for your reply.