I have a similar problem with my setup (Growatt SPF5000 + Growatt Ark batteries), and I think I figured it out.
Growatt support replies fast but they are not very helpful, the seller also has an engineer, but I seem to know more than they do.
I'm in a cold weather area (goes down below -20F in the winter) and the inverter + batteries are installed in a shack (not heated, and not insulated). It's installed in a remote area, to supply an offgrid cottage, I only visit once every couple of weeks.
I noticed starting Dec, when weather went below freezing that the inverter would not "run" for several days in a row and I just blamed the weather (not enough sun, as my panels are also not perfectly inclined/oriented). Then I noticed in some days it would "run" and the panels would produce plenty of output. So I started to debug, and my conclusions are as follows:
On one side, the batteries stop charging when they drop below 5 degrees Celsius (41F). Growatt support confirmed this, although the manual says they charge above -10C / 14F (with less amps), I guess that's a typo in the translation from Chinese. So, if not warm enough, the batteries will not charge. I noticed when the batteries are cold, the inverter initially shows nothing (no charging), then as they get warmer it shows it supplying energy, but almost nothing (something like 0.1A), and only when they are really warm enough (above 41F?) they start charging properly. It's hard to tell, as the batteries have their own insulation, so there can be a big difference between the cells temp and the ambient temp.
I found a solution, with an insulation box for the batteries, a smart thermostat and a heating pad for terrariums. I'm now monitoring it but so far it seems like it works well. The heating pad is only 15W but seems to be enough to warm the enclosure. Of course, it also has to be monitored summer time to make sure they don't overheat.
On the other side, the other problem is the inverter has the normal operation mode, which works when you have some kind of input (PV/batteries), but if none is available it goes into "stand-by". The problem is resuming from stand-by. Not sure yet if it's the power saving setting (I will see next time I go there, the ShinePhone app shows all settings but that one), but what I can say for sure is the inverter does not go back automatically from stand-by to supplying AC. It only charges the batteries. So only when the batteries have enough SOC they will trigger it, and supply AC. I'm sure as I tested this several days in a row, and as morning and sun comes, the inverter starts supplying the batteries, charging them until they reach a certain SOC, then the batteries start the supply to AC, which also triggers the inverter into normal operating mode. This can be forced also with low battery if you reset the inverter (stop batteries, stop DC input, then restart), but of course this only works if you are there.
So I don't think it's faulty hardware, rather faulty firmware setup. If it would be hardware, a simple reset wouldn't fix it.