I see. I believe it's not directly related to Amethyst / your behavior.

I've never simulated the issue on pc-connected dev device so I asked people for help with turning on debug level logging on their wallet.

Outcome is that based on various factors, but multiple zaps  processing over longer period of time is a major one - wallet needs to process them sequentionally.

Seems like android is interrupting such longer lasting processes at will, causing the errors you experience.

Working on change that would significantly shorten the processing needed on device, but will take some time.

Until then, there is a fix I've sent in other note.