Among your examples, this follows the appropriate syntax for expression variables.
Are you sure your syntax is the problem? Does the webhook task include other data updates that work? Does the task have the right table selected in its properties?
An alternate approach would be to create an action within the app that increments the column value and then call that action from the API rather than the generic “Edit” action.
is their a limit to how many rows you can edit via api? i got the increment to work but it stops at row 25. Does calling an action via api just as effecient as api edit?
Not per se, although it can time out–for example, if the edits trigger complex recalculations in other columns. I’ve used the API to process 1000s of rows.
Confirm that you included in the API call all the rows to be edited.