It seems like you want to keep all the fields from your original data, but for anyone who runs into an issue where Excel may have detected a ton of fields that are junk and need to be removed, I just wanted to point out a functionality I missed for longer than I would have liked; you can highlight all of the fields you want to remove and use the option Deselect Highlighted Fields rather than clicking on each checkbox individually:
The question seems answered, but here are a couple of screenshot for additional clarity. Whenever you view the results without the browse tool, you will be able to see the top rows only up to a pre-defined amount of MB, which usually ends up looking something like this:
In this example, only the first 6,832 rows out of the total 9,180 are being shown because that's how many rows fit within Alteryx's memory limit for the results preview shown on the anchors.
However, because you have 2638 fields, it seems that two rows would already be past the memory limit, and Alteryx therefore only shows the one row. If you ever wanted to override the system settings for the memory limit per anchor, first open your User Settings:
From the User Settings window go to the tab that says Advanced:
From here you can change the memory limit or disable the limit completely (not recommended).