A couple of days ago my game allowed me to have the first 30 gold bars free of charge but you then have to purchase a new piggy bank ( pink instead of gold) to collect more or you will see the gold bars fly off the screen.
It sounds like a technical issue so I will have to leave it to someone more qualified to answer. My game allowed me to open gold piggy bank for free a couple of days ago and replaced it with pink one, but I am on windows 10.
Welcome to the community everyone. I have had a similar problem. Usually if you see the circle up in the corner it means it is trying to establish a good internet connection to complete the transaction. Certain activities in the game can be done without an internet connection but other things - like purchasing gold bars from the piggy bank, must have an internet connection. @Timmi - make sure to check your connection (maybe even power your device off and on) and see if that helps.
@mishh48 - just a few questions - what platform are you playing from? Do you have a good internet connection? Is it possible to take a screenshot of what is happening? The more information we have the better we will be able to help you out.