I am experiencing the same situation in all my workflows.
Using Chrome browser (never tried other) 95% of the executions goes ok. But the other 5% UiPath fails to identify a screen element.
It is never the same element. Sometimes it´s the “User” attribute, sometimes it´s the “password”, other times is a button.
The fact is those elements are not changing any Selector information. Is i close the browser and restart the robot, it goes ok.