This is the NMI developer. There is most definitely an issue with Android 4.3 and the Nexus 10/Nexus 7 2013. The issue is that sometimes the USB Host Manager starts before the kernel has finished creating the USB device special files. The upshot of this is that Android apps can not access the devices. This is an issue in Android and NOT NMI. It appears there is a fix checked into the Android source and it should be released with Android 4.4.
If you use the new OTG Troubleshooter in NMI, it will detect the issue. You can tap "More Info (Web)" for a work-around. There is also another issue with the Nexus 7 2013 that requires the device be started as English (United States). Again, this is a Android issue and can not be worked-around in NMI. Hopefully, that will also be fixed in 4.4.
Finally, there is has always been an issue with the Nexus 7 3G, where if it is started with the OTG attached, it will have the same issue.
Anyway, all of these are Android bugs that affect all apps that use USB devices (root is different because it goes directly against the kernel). This include NMI, Gallery (MTP Camera Connections) and apps. that connect to MIDI keyboards.
As forums can get out of date, I recommend checking my blog post, where I keep this up to date:
Nexus Media Importer
If you use the new OTG Troubleshooter in NMI, it will detect the issue. You can tap "More Info (Web)" for a work-around. There is also another issue with the Nexus 7 2013 that requires the device be started as English (United States). Again, this is a Android issue and can not be worked-around in NMI. Hopefully, that will also be fixed in 4.4.
Finally, there is has always been an issue with the Nexus 7 3G, where if it is started with the OTG attached, it will have the same issue.
Anyway, all of these are Android bugs that affect all apps that use USB devices (root is different because it goes directly against the kernel). This include NMI, Gallery (MTP Camera Connections) and apps. that connect to MIDI keyboards.
As forums can get out of date, I recommend checking my blog post, where I keep this up to date:
Nexus Media Importer
Facebook
Twitter
Instagram