I had exactly same issu with Eastron SDM630, i tried all the cable tricks, shielded non shielded, multiple pairs, resitors and what not, even gave cable strait to meter n ot running it ducts, same.
I then asked to upgrade firmware they upgraded to
MAIN:2006-F150-1807
HMI:1001-C04B
Wersja protokołu:0104
Numer wersji akumulatora litowego:20AA
Arc Board Firmware Version:D207
I was happy for a while but then noticed, now when its discharging from battery it's still pulling some energy from the grid. Before it was functionning correctly export to CT from battery = zero pull from grid. Now i see it always pulls from grid on every phase at least 80W + if put load on it like 2k on one phase it pull from grid 800W from that phase. I can see that on meter and on Deye, before it was working perfectly (o pull from grid) just those warnings.
Im guessing they fixed calculations by just letting going lower on grid to not hit 0 on meter