H501A: Video Recoring does not Stop in X-Hubsan on iOS

[me_7b60d3xzEu]

I have baught H501A model recently and installed X-Hubsan from the App Store on my iPhone. Facing the problem that video ecording starts but does not stop afterwards. Pressing stop button in the application takes no effect, timer continues to count down. If I power off the device at some point, recording is obviously lost (sinceit is not saved to SD card properly due to power off).

Things tried so far:
- SD card is class 10 Kingston 16 GB
- SD card is formatted as FAT32 with 32KB allocation block size (as sugested at https://www.facebook.com/hubsan001/posts/back-to-basics-15-micro-sd-specifications-and-formatting-for-the-h501s-h501m-h50/1785092691795746/)
- Card is inserted to the turned off copter
- Sometimes (1 time out of 10) recording is stopped correctly and video is saved (succeeded a couple of times when tried indoors)

Don't really have an option to buy / test another SD card for now , but any other help is appreciated.
Thanks a lot.