how do I make my apple wireless keyboard work seamlessly with mac OS and bootcamp.

Hey all,
I have the apple bluetooth keyboard with the button on the side. Last night I paired this keyboard with my iPhone to do some writing, and when I went back to use it with my mac, it wasn't working properly. Normally I can switch between Mac OS, and windows 10 using bootcamp and not have any issues. Now, The keyboard is only wanting to be paired to only one OS at a time and not seamlessly transition the connection when I restart my computer. Any help would be appreciated. I've spent all day looking online for a solution.