Somehow I missed this thread. Good thing Arne PM'd me about it.
Ok let's try to take things from one angle cause right now we're allover the place.
Firstly, try to flash a stock 4206. To see if it's something related to the mod. There's 0.001% of that happening but in order to be diligent we have to rule that out. Actually the only chance of that happening is that the OROM version in the modded 4206 is somehow incompatible with your particular drives. This we can fix. I can mod for you a 4206 with the OROM that worked for you with 3602. And that would be the easy stuff.
If flashing stock produces the same results then it's one of two possible causes:
1) These new versions don't behave properly with something on your system.
2) You have corruption in some other region of the SPI (not the BIOS region), that seriously breaks these versions but doesn't affect the previous ones.
In case it's no 1 you'll probably have to wait for a newer version that fixes issues or stick with the older ones. (you can also remove hardware and test to locate what exactly is causing it -- I'd start with RAM..try another kit and with single DIMM connected only, in the slot furthest from the CPU).
In case it's no 2. First try switching to the 2nd chip and copy that to the 1st. Then switch back to 1st and flash it. If you haven't tried that already...
If that doesn't work then it means the 2nd chip could also be affected and we can try a recovery procedure with FTK to make sure the SPI flash is OK. In that case let me know so I'll give you directions. If that doesn't make any difference then it's case no 1 for sure.
PS And no I don't make tsipouro myself but I got friends and relatives that do. And it's of the highest quality
😛 And I can code perfectly fine while drunk I assure you, let alone do a simple UEFI mod
😛