I have been using monthly Amazon CSV Line Item based import for quite some time and it has been working fine.
For the month of Dec 2021, looks like “Item Subtotal Tax” column in CSV is completely 0.00 and it is messing up the import as all none of entries in credit card match the [Amazon Order] entries added through importing 
Any suggestions on how I could address this without having to fix it all manually?
Hi @wizavi,
I haven’t seen any missing or incorrect values in the Item Subtotal Tax column for our December reports (once they finally ran). I know that reports were having difficulty processing for a couple of weeks, so maybe there were some errors during that time as well. Have you tried running the report again?
I requested for a new report but it is still stuck in “processing” 
Yes, there still seems to be some intermittent slowness with running reports. I started one about the same time I replied to your post and it finished sometime overnight (PST). I ran another one just now and it finished within minutes. Both have the proper values in the Item Subtotal Tax column.
My second report also has the whole column of “Item Subtotal Tax” completely $0.00.
Just for kicks I tried downloading the third time and this time the file got downloaded in a min and also issue got fixed 