The main problem of IC market is, they freeze the trading chart during high voltage news session; worst experience on news trading!
That doesn't just happen on ICMarkets, infact also a few other brokers that i used before in AUS.
But prefers not to name them.
one of the issues of these retail brokers is they have too many clients on a single Server. So changing server doesn't really help because there are so many orders going through. And because they probably are not a STP A Book broker, they have internal B book plus C Book for hedging and throwing out, this caused massive delay especially during the high volatile period. Thus explained, why orders may not be filled as well as heavy slippage. The connection is already having a bad time plus other attributions like Your own VPS or computer and so on.
So it's very common to experience server going down, freezing etc.