When validation fails on firefox, I get redirected to the welcome view, chrome works fine.

I recently was testing out firefox, was using a site of mine. During a form post with 3 fields, a select input, upload input, and a text input.

public function uploadPost(Request $request)
    {
        $this->authorize('isadmin', new Upload);

        //Make sure the data from the request is valid
        $request->validate([
            'name' => 'required|string|min:3|max:100',
            'fileUpload' => 'required|file|mimes:audio/wav,audio/mp3,video/mp4,audio/mpeg,application/doc,application/docx|max:16484',
            'group' => 'required|integer|min:1|max:50',
        ]);

        $upload = new Upload;
        $upload->name = $request->name;
        $upload->group_id = $request->group;
        $upload->extension = strtolower($request->file('fileUpload')->extension());
        $filename = $request->file('fileUpload')->store('recordings');
        if ($request->file('fileUpload')->isValid()) {
            $upload->filename = $filename;
        }
        if ($upload->extension == "wav") {
            $upload->mime_type = "audio/wav";
        } elseif ($upload->extension == "mp3") {
            $upload->mime_type = "audio/mpeg";
        } elseif ($upload->extension == "mp4") {
            $upload->mime_type = "video/mp4";
        } elseif ($upload->extension == "doc" || $upload->extension == "docx") {
            $upload->mime_type = "application/msword";
        }
        $upload->save();

        $request->session()->flash('success', 1);


        return redirect()->back();
    }

Currently when I upload a file that doesn't pass the validator due to an incorrect mime type, chrome sends me back to the same page and I can view the errors at the top. Microsoft Edge does as well.

Chrome, Chrome Canary, and Microsoft Edge work properly, I see my post form with the validator errors above it.

Firefox v60.0.2, takes me back to the base welcome view and i end up at http://mysite/

Why does this happen?

*Edited.