I'm using the mobile site as I type and it is working just fine. The mobile site is limited to what it can do though, just like any mobile site. One thing you could do (assuming you decided to continue using the mobile site more) is swap to the full site, upload whatever it is you are uploading, then swap to the mobile site. Or do like I do and use an external hosting site like photobucket and just grab the IMG code and paste it here.
EDIT: So for an example, after posting this I went to my photobucket app, and grabbed a code. I will leave you with a dancing reindeer.
If you go to m.ford-trucks.com on your phone, then click "Forums" on the nav bar you should receive a prompt asking if you would like to view the mobile template, click ok and it will take you to the mobile version. If you click no, you will not receive that prompt again for 24 hours, since it cookies your response and see the normal site. Let me know if you still have issues.
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