Go to Bannerlord Settings (the cog in steam) -> Properties -> Controller: Enable "Steam Override"

Once that is set, go back to main page of bannerlord, and click on "Controller Overlay" on righthand side near settings icon.


Click through the tutorial pages, then find "Templates" and select "Keyboard (WASD) and Mouse" as seen below.


https://steamuserimages-a.akamaihd.net/ugc/2048614092320791212/753FDCDA4BBD7F01A4CD0048F1396C3E98C2A4F2/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false

This will prevent the graphical bugs of the cursor flashing and the game with load the "Gamepad" of your keyboard upon launch. Incredibly frustrating this is not natively supported in Bannerlords as of now.