This happens when an invoice is coded to a Tax Group in SageAPA that is not associated with a Tax Authority in Sage 300.
There are two ways you can resolve this depending on the scenario. You either need the invoice to have taxes recorded, or you do not.
If you need to code the invoice to the Tax Group (because it has a Tax, Tax Group and Tax Amount that you need to record), then you must make sure your Tax Group is associated with a Tax Authority in Sage 300. Once you do that, you can sync your invoice again (it will be in SE status) and it should import into Sage 300.
If the invoice does NOT have a Tax, Tax Group and Tax Amount you need to record, then reset the invoice and ensure the Tax Group, Tax and Tax Amount is all left blank (use the X to clear the values) and then resubmit for approval and sync into Sage 300.