Look... Jens was crystal clear
As stated in the manual, the ACA500 is a low-budget product where tiny flaws are expected. We indeed have a set of a few CF cards that don't work at all and others that cause trouble when re-booting (either with or without early startup menu), and we can't make those work, mainly because there's no development budget left to support those cards.
Next time before
you buy something ask how much the development budget is going to be and how long this budget will last to support those cards.
The ACA500 was released only a couple of months ago, some time in December 2013 with a 0.xx flash version.
Right now after only a couple of months the flash version is 0.99 and there's no development budget left to support those cards
Grab a copy of the 0.99 flash and get one of the working CF cards