S3 Download Query Corrupts .XLSX Files

I used the S3 template to successfully implement an upload + download feature for my app. It works wonderfully, except for .xlsx files for some reason. I'm unable to actually open the files as Excel errors out saying "This file is corrupt and cannot be opened". I had a problem with .csv files as well.

.png, .pdf all seem to download without issue.

If I download the same .xlsx or .csv files straight from the S3 browser on AWS, it downloads without issue and is complete corruption-free.

Any ideas?

I've worked around this by generating a signed URL via my S3 resource and just opening that URL on button click. So far, this seems to have fixed any issues with downloading files from S3.