This comes up often since Amazon has historically and frustratingly limited the lookback period for Advertising data to 60 days with some variability amongst the ad types.
Unfortunately, we cannot currently backfill data further than 60 days upon initially connecting one of your advertising sellers or vendors. Even if you have the data stored somewhere, we can't upload it into our system due to compatibility and data integrity issues.
With that said, we have heard from Amazon that they will soon allow providers like us to pull up to 13 months of historical campaign data via the API. This would help immensely. The timeline for this sounds like late 2024 or early 2025 but we won't know for sure until they release this feature.
If you have any questions about this, please email support@mixshift.io, thank you!