Am I doing something wrong or is the spread in test mode with marketVal() not propperly supported?

Code:
function tick() {
	if(is(TESTMODE))
		Spread = marketVal();
	printf("n%04d-%02d-%02d %02d:%02d:%02.3f, %s: %.5f, Spread: %.5f", year(),month(),day(),hour(),minute(),second(),Asset, priceClose(), Spread);
	}
}

function run() {
  LookBack = 0;
  History = ".t1";
  StartDate = 20180302;
  set(TICKS+LOGFILE);
}

produces following log:
Code:
V 1.797 on Sun 18-03-04 12:56:33
Test: ShowSpread EUR/USD (TICKS) 2018
2018-03-02 01:00:0.033, EUR/USD: 1.22735, Spread: 0.00000
2018-03-02 01:00:0.233, EUR/USD: 1.22734, Spread: 0.00000
2018-03-02 01:00:0.420, EUR/USD: 1.22734, Spread: 0.00000
2018-03-02 01:00:0.996, EUR/USD: 1.22733, Spread: 0.00000
2018-03-02 01:00:1.002, EUR/USD: 1.22731, Spread: 0.00000
2018-03-02 01:00:1.027, EUR/USD: 1.22729, Spread: 0.00000
2018-03-02 01:00:1.043, EUR/USD: 1.22728, Spread: 0.00000
2018-03-02 01:00:1.109, EUR/USD: 1.22729, Spread: 0.00000
2018-03-02 01:00:1.216, EUR/USD: 1.22728, Spread: 0.00000
2018-03-02 01:00:1.308, EUR/USD: 1.22728, Spread: 0.00000

while the corresponding .t1 (in ZHistoryEditor, downloaded from FXCM with assetHistory(Asset,0)):
Code:
2018.03.02 01:00:01.308	1,22728
2018.03.02 01:00:01.308	-1,22727
2018.03.02 01:00:01.215	1,22728
2018.03.02 01:00:01.108	1,22729
2018.03.02 01:00:01.043	1,22728
2018.03.02 01:00:01.026	1,22729
2018.03.02 01:00:01.002	1,22731
2018.03.02 01:00:00.996	1,22733
2018.03.02 01:00:00.996	-1,22732
2018.03.02 01:00:00.419	1,22734
2018.03.02 01:00:00.419	-1,22732
2018.03.02 01:00:00.233	1,22734
2018.03.02 01:00:00.233	-1,22733
2018.03.02 01:00:00.033	1,22735
2018.03.02 01:00:00.033	-1,22733