Yeah, falls into a weird technical hole.
The first part of the SELECT() - that’s missing the select - is a formula for a list:
(HazardSelected[HazardID], So that’s valid.
And the second argument of SELECT() is to determine if the list the SELECT() is providing should be restricted to unique records… so since [HazardSelected]=“TRUE” is a true/false statement… it’s valid.
If the formula parsing was a little tighter on AppSheet’s end, it might have cought the missing SELECT. (But it’s fine as it is! DON"T change it. (^_^) It’s right in that Goldilocks zone, just enough wiggle room when you need it. )