Why does sometimes the debugger step into an on click sub when I'm setting a check box variable? Excel VBA

I'm trying to sort through some checkbox code that worked fine for a long time and all of a sudden doesn't work. It steps through in the debugger but throws errors on click.

When troubleshooting though, I set the checkbox values on open workbook but when I step through that code, sometimes when it hits:

Sheet1.CheckBox26.Value = True

It will actually step into the "On Click" sub. Other times it does not. In both cases I'm using F8 to step through the code.