This is an error I have ran into from time to time as well, with different root causes. My first suggestion is to double check that when you are modeling the application you are interacting with that Match Index is always used as an identifying crite...
Both {LWin} and {RWin} should work. There is a list of Global Send Key Events starting on page 8 of this document:
https://portal.blueprism.com/system/files/2017-12/v5%20Surface%20Automation%20-%20Training%20Course.pdf
