Utility meter missing data

I wonder if someone can assist me with an issue that I am having with utility meter
I am using Octopus Integration to pull all our gas and electricity usage.
Using that data I am trying to get monthly cost data calculated using the utility meter helpers. So for example for the gas usage:
From the Octopus energy integration I use Current Accumulative cost sensor - that has the standing charge and used gas cost added together.
However when I use that with the Utility meter it somehow misses the initial value of that sensor (so the daily standing charge).
So for example:
Current Accumulative Cost is right now £0.67
and the Utility Meter measured Monthly cost is showing only £0.40
so the difference £0.27 is the standing charge, why was that missed? Why is utility meter missing that value? How can I fix this?