I noticed that it doesnt happen if you wait until tow truck disconnected to start engine 1. Basically, I use FSR, GSX and the Fenix normally. During pushback, I start engine 2, and I wait for the tow truck disconnection and the nose to be back on ground to start engine 1. Dont had any brake temp issue when proceeding like this. BTW, it had also happened to me a few times without using FSR. Im sure its a GSX problem. But without FSR, it happened only on random occasion. With FSR, it happened 100% of the time. But my technique should work, regardless if you are using FSR or not.