Hiya,
Apologies for the delay, I could only contact the user today.
Thanks for the insight into the monitoring tool. That has been really helpful. here's a section of the monitoring data that is relevent to the issue...
"x-sharepointhealthscore":"1","x-sp-serverstate":"ReadOnly=0","x-ms-client-request-id":"eb13ce23-4cb0-4f22-b123-ac773a7fa5bb"},"body":"{\r\n \"status\": 400,\r\n \"message\": \"Invalid URL value.\\n\\nA URL field contains invalid data. Please check the value and try again.\\r\\nclientRequestId: eb13ce23-4cb0-4f22-b123-ac773a7fa5bb\\r\\nserviceRequestId: eb13ce23-4cb0-4f22-b123-ac773a7fa5bb\"\r\n}","responseType":"text"}}},{"time":1707987293347,"category":"Function","name":"Patch","logLevel":4,"data":{"errorMessage":"Network error when using Patch function: The requested operation is invalid.","raiseToastNotification":false,"wasReported":false,"error":null,"functionName":"Patch","context":{"entityName":"Button1","propertyName":"OnSelect","nodeId":4,"id":1420},"info":"Network error when using Patch function: The requested operation is invalid."}},{"time":1707987293348,"category":"Runtime","name":"submitFormAsync","logLevel":4,"data":{"context":{"entityName":"Button1","propertyName":"OnSelect","nodeId":4,"id":1420},"info":"One or more errors has occurred.","dataSourceErrors":[{"Record":null,"Column":null,"Message":"The requested operation is invalid.","Error":8,"ServerMessage":"eTrackers failed: Invalid URL value.\n\nA URL field contains invalid data. Please check the value and try again.\r\nclientRequestId: eb13ce23-4cb0-4f22-b123-ac773a7fa5bb\r\nserviceRequestId: eb13ce23-4cb0-4f22-b123-ac773a7fa5bb"}]}},{"time":1707987293353,"category":"Function","name":"Patch","logLevel":4,"data":{"errorMessage":"Network error when using Patch function: The requested operation is invalid.","raiseToastNotification":false,"error":null,"wasReported":false,"functionName":"Patch","context":{"entityName":"Button1","propertyName":"OnSelect","nodeId":4,"id":1420},"info":"Network error when using Patch function: The requested operation is invalid."}},{"time":1707987293353,"category":"Runtime","name":"Unhandled error","logLevel":4,"data":{"errors":[{"Kind":8,"Message":"Network error when using Patch function: The requested operation is invalid.","Source":"Button1.OnSelect","Observed":"Button1.OnSelect","Details":{"HttpStatusCode":400,"HttpResponse":"{\r\n \"status\": 400,\r\n \"message\": \"Invalid URL value.\\n\\nA URL field contains invalid data. Please check the value and try again.\\r\\nclientRequestId:
It seems to be an issue with the format of the URL. It's just odd that this isn't an issue for anyone else and he can amend an entry in the SP list through the app but cannot add a new one.
We have tried two separate browsers and on two separate machines and I have removed him from the SP list and re-added him.