Hi! A few things to help you with future posts:
You will want to post questions or other help in the “Questions” category. You will get more eyes seeing your post there and a greater possibility of quicker assistance. “Resources” needs to be reserved for posts about items that can help us in building our apps such as third party services. @Steve
Using the tag of “bugs-issues-errors” should only be used for items that you think are a defect or flaw in system and needs corrected by AppSheet.
To better serve you and resolve your issues, please post details such as expressions, screenshots, etc. Without them we can only guess what is causing your trouble.
Ok, so now that’s out of the way…
It would be a great help to yourself if you could provide the expression that results in the error you’ve indicated.
As you know, the MAX() function requires a list of values to determine the maximum one. That can be either a List column type OR an expression that can return a list of values.
For example if I have table named Orders with a column named Total and I want to see what the highest total amount is I can use the MAX() function like so:
Orders[Total], returns a list of the Total amount from each order in the Orders table.
SELECT() and FILTER() functions can also return lists and be used inside of the MAX() function.