I had similar issues in my testing with 1.0.2.5. I havnt tested with .7 but I will try to tomorrow.
Leave the USB limit at 45. Higher can work but I would start getting random failures the higher I went. I could also duplicate this in other capture apps. Also it doesn't seem to make much difference.
When you get into that "first frame works, others fail" you need to reboot. This seemes to be directly linked with upping the USB Limit. Unplugging the camera did not work. Only thing to fix it was a reboot, like the low level driver was in an odd state.
I'll grab the latest ascom driver and see if that changes things. With 1.0.2.5 things were pretty stable as long as I left the USB Limit alone.
Thanks
Jared