Adding form control checkbox causes execution issues in Excel

I have a specific spreadsheet and macro that we use for a request system internally. I want to add a simple checkbox for the user to signify they want something special to be done with their request. I added a form control box and supplementing code for what happens when that box is checked. The problem I run into is when I'm going to clear contents from a selection it gives me a Run-time error '438': Object doesn't support this property or method. Yet when I debug, bring the highlighted cursor back up to the selection line above it, press F8 to step through the code again, it works just fine.

If I change nothing in the code itself, but delete the Form Control checkbox, all runs smoothly. I'm at a loss as to what to even search and didn't have any luck. I figured the fine people on these boards could set me straight.