The KIWI SDR site uses the Wellbrooks Loop, but sometimes very very rarely it cannot receive it either, I just remembered. But most days it hear it very well.
My QTH is northern part of UK, and the SDR site is in Southern UK.
Yeah, I can see your point on the propagation path causing it, because sometimes I hold my XHDATA D-808 with the whip antenna, and when I move around in the room, on some spots it hears weak stations very well, but by just moving away a few steps further, it totally loses it.
My receivers are a few, but mostly I use a Sangean ATS-803A, Realistic DX-392, and ICOM IC-751A transceiver, TECSUN PL-660 and XHDATA D-808.
I will try 11710 Khz, if timing is OK with me. But I seem to hear better on 9515 and 9740 for RK schedules which is late afternoon and evenings. But this 15575 has been always very very difficult copy due to the weakness in signal. I was wondering if my antenna needs some height at least about 10m above the ground and clear? Because my 30m long wire is only about 1.8m above the ground being also used as drying washed clothes.