I'm creating an automation that performs the following tasks:
On Trigger (manually), the automation is to sum up original estimate to an Epic custom field called Total Project Estimate. The rule retrieves all child tasks linked to the epic using JQL. It also retrives linked "Idea" issue to retrieve the original effort on the idea. Then, it takes the values of all child tasks and the original estimate of the idea and sums them up to the custom field Total Project Estimate.
The issue I'm having is that the calculation in the variable is mibehaving 
When you look at the audit log you can see it clearly, but I'm banging my head trying to figure out the error of my ways.
Here is the audit log and rule:
It looks like a variable issue:

