Good morning @timl ,
this is strange.
Should I mention that when running the test, there is no error
Of course the SQL will not update
and when i close the test of the app, i will notice a formula error on the button
when i hover over the error it will come up with

if i remove the id completely, then it will fail and the error will be replaced with another one, "ID required"
Is your SQL updating? no errors if you exit the test?
again, the script i write is
Patch(event_log, Defaults(event_log), {ID : GUID(), Serial_No : SerialNumberTextInput.Text, Status_Event : "new", TimeStamp : Now()});
I have tried to put the patch script at the beginning , middle or end of the updateif
Any other similar function maybe?
Thank you again