This is a member to member forum we are buyers and sellers like you . That being said we can't fix it.
I have the eBay app on my iPad never had an issue.But then I don't use it much I mainly have it for the cute Cha-Ching sound I get when I make a sale. As for your issue could be your iPhone have you updated your iPhone? Is your iPhone and older model? Could be you need to speak to Apple about your problem.
