I saw a video on youtube (search for "USB OTG does work on Huawei ascend mate 2") where the person talks about the "Nexus Media Importer" app that works, though it costs 3.99. There is also a free version called "Nexus Photo Viewer", you can check if your USB will work using this free app. I tried and was able to view files on my USB.
My issue was printing via USB OTG and now using the Nexus Photo Viewer coupled with Print Hammermill app I am able to print via USB.