That little blue radar in the corner of your screen indicates unstable server connection. If this occurs, make sure you have stable connection before, for example, starting an attack.
Verify that you’re properly connected to Wi-Fi, or in a spot with stable network strength (e.g. try not to attack when in means of public transportation).
Should connectivity break during a battle, the game will attempt to simulate the battles through, which could create some discrepancies in Battle logs and replays.