Yes I have same issue with my twin LV6548 in 120/240 v running 18 months . Yes, Led lights flicker with a higher load draw like a coffee maker or simular loads. I just bought a new NKH low frequency inverter 10 kw to change over soon. I monitor with solar assistant, no internet connection. Biggest LV6548 complaint is 250 v maximum PV volt input. These were good units at the time but equipment has changed for the better over the years. Thanks for sharing your setup.

what's the power factor on your fridge and freezer? if they've got a restive start, resistive run compressor, they usually have only .5 to .6, which is likely going to stress out the inverter as it's seeing effectively twice the amperage draw from the reactive power being so many degrees behind the sinewave.

If there is a coupon on an item on Amazon after you place an order sometimes i have been able to place another order. Ir you could get someone else to place orders for you with you credit card if you trust them a lot.

The fridge and freezer on the same leg, right? Do you have a bad, loose ground?

These high frequency inverters are far too noisy and they don't offer any galvanic isolation for safety. They also offer a far poorer surge capacity and a shorter life expectancy than real inverters that use longer lasting, higher surge, low frequency, transformer based inverters.