Oh I see, provide the easy and obvious answer. 🙂

I agree that this is equivalent.

This will work

SomeVal2 = 'ABC' or SomeVal is not null

This won't but I don't think I really need the CONVERT in the WHERE

SomeVal2 = 'ABC' or CONVERT(decimal(20,6), SomeVal) is not null

Definitely a data issue though. I rolled back my prod database and after new data load the existing code works. I can still duplicate the error in test.

thanks