Alpha Channel Not working - Media Encoder

Hi there,

Before you read this, please be aware I am very much a novice so i apologise if the explanation is poor!

For quite some time I have been trying to figure out how to convert a file (more specificially, a timer) and encoding it using the HVEC (H.265) setting. I currently edit videos on Lumafusion on my iPad and due to restrictions in place by Apple alpha channels were not supported... until now! Regardless, I have tried converting the original file to HVEC using media encoder (I have access to a full version), however, whenever I import it to the ipad, there's no transparency maintained. As the timer counts down, a line around the edge of the circle disappears in line with the coundown. At 10 second intervals, a white circle appears around the edge momentarily to emphasise the time. Consequently, the alpha channel is very important!

 I wanted to reach out to see if I am going massively wrong somewhere. The attached image details the propeties of the ORIGINAL file. 

Any help would be greatly appreciated - I am also a complete novice when is comes to media encoder (managed to access it through my school) so it may be I'm simply not going through the process correctly.