HTTP Error when uploading zip file

For some reason, I'm getting an HTTP Error when I try to upload a 14mb zip file to my media files. I have an upload limit up to 250mb so the problem doesn't lie there. My host just told me that WP doesn't accept zip file uploads by default... which I find strange because I've been able to upload zip files in the past fine!

Does anyone have any insight on why this is happening? Have you ever experienced this before? What can I do to fix this issue?

Thanks for your help!
Sinoun