How can I use macros for revision tracking in Access 2016?

When a field is updated, I want a macro to add information about that change to an audit table. All I need is what changed (table, record, field), the old and new values, and the date/time of the change.

I've tried updating via form vs table, changing data types, creating named macros rather than using After Update, and a bunch of other tweaks, and I've referenced various official and unofficial documentation/forums/tutorials (including ScottGem's "Audit Trail using Data Macros", Access programming articles at the Microsoft support site, and several entries at databasedev.co.uk).

I'm troubleshooting this issue by using simplified data in a new, blank database to avoid leftovers from previous attempts:
tblAudit has one manually-entered record with fields for ChangeID (AutoNumber PK) and TableChanged, RecordChanged, FieldChanged, OldValue, NewValue (all Short Text), and ChangeDate (Date/Time).
tblVendors has two records of sample data over three fields (VendorID as AutoNumber PK, plus VendorName and Phone as Short Text). I added an After Update macro through the Table tab's After Events section (below). This time around, I haven't changed anything else.

When I change the first record's VendorName field, I expect the macro to create a corresponding record in tblAudit, but I don't see any changes. What am I missing?

Code formatted for legibility:

<?xml version="1.0" encoding="UTF-16" standalone="no"?><DataMacros xmlns="http://schemas.microsoft.com/office/accessservices/2009/11/application"><DataMacro Event="AfterUpdate"><Statements><ConditionalBlock><If>                    <Condition>                            Updated("VendorName")</Condition>                        <Statements>                        <CreateRecord>                          <Data>                              <Reference>                                        tblRevisionLog</Reference>                                    </Data>                             <Statements>                                <Action Name="SetField">                                    <Argument Name="Field">                                            tblRevisionLog.TableChanged</Argument><Argument Name="Value">"tblVendors"</Argument>                                     </Action>                                   <Action Name="SetField"><Argument Name="Field">                                            tblRevisionLog.RecordID</Argument><Argument Name="Value">                                            [tblVendors].[VendorID]</Argument></Action><Action Name="SetField"><Argument Name="Field">                                            tblRevisionLog.FieldChanged</Argument><Argument Name="Value">"VendorName"</Argument></Action><Action Name="SetField"><Argument Name="Field">                                            tblRevisionLog.OldValue</Argument><Argument Name="Value">                                            [Old].[VendorName]</Argument></Action><Action Name="SetField"><Argument Name="Field">                                            tblRevisionLog.NewValue</Argument><Argument Name="Value">                                            [tblVendors].[VendorName]</Argument></Action><Action Name="SetField"><Argument Name="Field">                                            tblRevisionLog.ChangeDate</Argument><Argument Name="Value">                                            Now()</Argument></Action></Statements></CreateRecord></Statements></If></ConditionalBlock></Statements></DataMacro></DataMacros>

Edit 1: Just to be sure, I added a form to my simplified test database and confirmed that the data sources were correct. Changes to frmVendors still update only tblVendors, not tblAudit. Adding a macro to the form's After Update event doesn't work, because that macro builder doesn't have a CreateRecord option and I can't use RunMacro there since the macro tied to tblVendor's After Update event isn't a named macro.