Battery loosing charge

So I have recently got a Hybrid Inverter 5.0 Gen 3 and 2x Giv-Bat 9.5 installed in my house with a 8kw array.
I have is setup as follows: Eco mode ON, Timed charge ON between 2am and 5am at full power to full capacity and Timed discharge ON between 4pm and 7pm. Inverter is running on D0.303-A0.303 and the batteries are on 3012.
Everything ran nicely until yesterday evening when I noticed that at 7:30pm the battery SOC dropped quickly from 43% to 6% within 30 minutes with no house load or export. After this, the house started drawing from the grid to cover the needs and the battery charged normally between 2am and 5am.

What is this about? Has anyone else experienced something similar?

I'm seeing the same thing every 3 or days.
I think it's the OCV kicking in when the PV takes over the house load and the battery is resting.
Mine crashes to 4% or less every few days and then has to do a complete charge to 100% .....