There are 2 ways you can hookup Solar to the main panel:
line-side or load-side.
The majority of the setups use load side:
In Blue the CT (current transformers) that measure current for the “mains”.
It is effectively what the meter is registering.
In Yellow the PV generated output from the inverter(s)
Suppose the PV is generating 500 watt
The blue CT’s measure 1000 watt from the grid toward the breaker panel.
That means that total usage is BLUE + YELLOW measurements added = 500+1000 = 1500 watt
Now with the other setup: line or supply side setup:
This is getting more and more popular because of larger solar systems being installed and not running into the so called 120% rule of the busbar (I won’t even try to explain it 
)
But this is how it looks:
In that case blue is measuring only the load from the house.
The yellow CT’s measure (like the other situation) PV generation.
Sense now needs to calculate the amount energy through the meter by subtracting:
1500 (blue) - 500 (yellow) = 1000 watt is being pulled from the grid.
So sense needs to know what your setup is in order to do the calculations right.
It doesn’t ask you if you have load-side or supply side setup when you set it up.
It somehow does some magic and figures it out by itself, and it is not always right.
I have installed multiple sense setups and often it has switched back & forth between the 2 possibilities.
After contacting support, they normally fixed that within the next business day or so.
I am not 100% sure this is this is the case in your setup, but it could be.
I can understand your frustration that no solution has been offered after weeks.
Maybe @JustinAtSense could take a look at this next week?