[Plugin: WP-DownloadManager] Error in file size

All my downloads have a “n” in the file size.

I tried deleting the size and let it find the size automaticly, but the n keeps comming back.

Here are some examples.

(279n0 KiB, 1.480 hits)
(353n0 KiB, 257 hits)

How can I fix this?

https://www.ads-software.com/extend/plugins/wp-downloadmanager/