[David Cutler]

Stumbled upon another workaround this morning @Vince that I thought might be worth mentioning.

As I’m sure you are aware when you use a tool it automatically populates into a “Recent Tools” toolbox. What you might not realize is that if you change something in that tool during use – the layer assignment for example, the tool that appears in your “Recent Tools” includes that change. So, if your layer assignment disappears, you can set it the first time you use the tool in that session, and then re-use the modified tool from the “Recent Tools” toolbox, rather than your standard location.

While this falls firmly in @Doug McLean ‘s “I shouldn’t have to” category, it does work.