When you have x>, this means that the Condition block does 2 checks - one > for the current candle and another < for the previous candle. More info here: https://fxdreema.com/demo/mt4-crossover-indicators This means that the x> state... I mean the time period where both checks are true... can be up to 1 candle long. When that candle is closed, this x> is no more true. While if you use >, this remains true for all candles where one of the lines is above the other, until they cross.
But because x> remains true for multiple ticks (while the current exists), "Once per bar" is used to catch only the first one.
If you have 2 blocks with different indicators connected one after another and if x> (or x<) is used, then better don't expect both crossovers to happen at the same candle. Instead, leave x> (or x<) only in one Condition and in the other use > or <. You know, if now MAx is > than MAy, this means that MAx crossed MAy some time ago.
There is another kind of crossover as well - https://fxdreema.com/demo/mt4-price-vs-indicator