WP Offload media not upload PDF and CSV files

Hello, @WP Offload Media27 plugin is not uploading PDF and CSV files into the Amazon S3 bucket. I tried to debug but failed. I am currently using digital ocean hosting and PHP 8 with WordPress 6. While in logs I found this.

Mon Jun 26 19:59:07.256998 2022] [php8:notice] [pid 282] [client 100.60.20.119:40064] AS3CF: Error offloading /var/www/html/uploads/26/product_design.pdf to provider: Found 1 error while validating the input provided for the PutObject operation:\n[ContentType] must be a string or an object that implements __toString(). Found bool(false), referer: XXXXXXXXX

Please help me.