I always use OTG when flying my spark, the problem I found out when using the OTG is that the remote and spark have to be bind first before connecting the OTG to the remote. Hope this will help
What I usually did using the OTG is starting the RC first then the drone, after they both connected then insert your OTG cable to the RC. I used to do it that way and haven't experiencing any problems until now
Yup, I agree with @Dronason, spark is nice, and you have master it from basic, just follow your learning curve, and try to fly it step by step. You will know better your own spark, that's the way I learn mine too. [emoji4]
Maybe you can try using OTG cable to connect your phone to the controller, also check your flight limitation setting within the DJI Go apps, and disable the beginner mode