I have had the issue twice now in less the 1 hour. I am at 394 gems, won 8 on the wheel went to 402 the on my next wheel spin I was back at 394. About 6 races later another win on the wheel for 6 gems. This time whilst watching closely it went to 400 and then immediately back to 394.
Any idea what’s going on here?
Edit: I just got another 6 gems, the total so far has stayed at 400.