TWRP USB-OTG won't work? I have a nexus 7 (2012). I have installed the most ercent version of TWRP for it, and TWRP seems to work. Im trying to do this, and have reached the part where it says 


  Once Team Win boots, go into Wipe and select Advanced Wipe. Select all
  checkboxes except for USB-OTG, and slide to wipe.


Only USB-OTG didn't even show up in the advanced wipe partitions menu. The menu inlcuded:
- Dalvik Cache
- System
- Cache
- Data
- Internal Storage

I then trawled the internet and found (alas, can't seem to find it again) a thread on the xda-forums with with a similar question. It told me that a fix was to make sure that:


"Use rm-rf instead of formatting" was ticked on in settings
That USB-OTG was mounted in the mount menu


So i ticked "Use rm-rf instead of formatting" in settings then I went into the mount menu and I tried to tick USB-OTG. The option to select USB-OTG was there, but when I pressed it the box on the left didn't cross. I tested mounting and unmounting all of the other options to see if it was aproblem in that area. Nope, all the other mounted and unmounted fine! Selecting USB-OTG in storage didn't do anyhing either (as in I could press the icon to select it, but it wouldn't actually select, also the readout on this screen said USB-OTG had 0 data...)

Other than explaing or helping with all that, my question is also 'does it matter?'. Common sense tells me that if I don't have any USB-OTG connected and I just wipe everything in the advanced wipe, it will have the same effect as what the Guardian Project guide says? IDK but please help a noob out.

I'm fairly new to this (could you tell?) so all help is good, and I'm happy with command line 'deep' stuff (my main laptop which i'm using for this runs linux) including the TWRP command line.

Sorry for long post, didnt want to leave stuff out

Thanks
I formatted my pen drive in FAT file system and restarted the recovery. Then it allowed me to tick the USB OTG. And I could access all the files in pen drive inside TWRP. I used it to load the CM mod. FAT32 may also work though I haven't tested it.

Edit: FAT32 also works.