What's the difference of Invoice Amount in Contract Billing and Project Associated Tab?

Summary:

I noticed when I create a Draft Invoice from an event worth 38,000 , the Contract Line level in the Billing tab already gone up but the Invoiced amount in the associated projects tab is still 72,000

Content (required):

Looking for some explanation? Since I'm planning only to create a dummy Invoice with positive amount until transferred status then I will just do a datafix to make it accepted. I thought This will not affect the Invoice amount but it is affecting.

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