'Set row values' not working as part of a bot action

[Distantspaces]

I have created an action that should update a value for a column in a newly created row. I've included this action as part of a bot which should trigger when the new row is created. The bot is triggering fine and it completes successfully (thanks to help offered in another post), yet the value is not updated in my underlying spreadsheet. If I run the 'hello' action manually (through a button in the UI), the spreadsheet does update, so the problem seems to be in the bot.

According to the event monitor, the bot receives the following input:

....."Wheel Size": "24\"", "Unique ID": "A62", "Status": "", "Bike Location": "",.....

As an output for the 'update status' step of the bot, it shows this:

 ....."Wheel Size": "24\"", "Unique ID": "A62", "Status": "", "Bike Location": "",.....

 So even though it should update the status value to "Testing", the value remains unchanged, but no error is reported either. According to the Audit log too, the operation completes successfully:

Properties: 
{ 
"TableName": "Donors", 
"AppTemplateVersion": "1.000131", 
"DataActionName": "hello",
"Updated rows' keys": [], 
"AppTemplateName": "916e3c19-a84f-4a05-8796-4eb0fff66b07", 
"Operation": "Edit row", 
"RecordType": "Stop", 
"Result": "Success" 
}

I've spent hours trying to make this work, but still can't figure out the problem. Could the 'updated rows keys' being empty in the log above have something to do with it? I'm wondering if the bot doesn't know which row to update (because the action runs fine when I run it from a UI button in the record details view).

All help is appreciated.