@knamc_com my assumption is that both @alexnajm are and I are confused because your negative numbers are correctly being accounted for and your output looks correct. so we are not quite clear what you are expecting to see as a result? perhaps you only want to aggregate by date? or only by project? that would create fewer dimensions in your aggregation (ie more entities would sum.) Perhaps you want an output which is the universe of dates and projects - with the total sum for all the entries. if that's the case you would need to split your workflow - and do two summarize tools - the first to group. the second to just sume - and then append the two streams together.
Just one doubt is the field type of "Amount" is fixed decimal. I found the past discussion on malfunction of AMP engine when summarizing negative fixed decimal value, it was a bit old discussion though.
