Can someone confirm if I've identified a bug in Salesforce regarding formula fields?

Question

I believe I've identified a bug in Salesforce related to formula fields. Can some of my fellow developers, and admins too, confirm if I am observing unexpected behavior? I do have a workaround.

The issue is reproducible in the following manner in any developer sandbox using the Account and Contact standard objects:

1. Create a custom formula field on the Account object with the following attributes:

   Field Label = Test Formula Test Feld - Account
   Field Name = Test_Formula_Text_Field
   Field API Name = Test_Formula_Text_Field__c
   Type = Text
   Formula = "Test Value From Account"
   

2. Create a custom formula field on the Contact object with the following attributes:

    Field Label = Test Related Formula Text Field - Acct
    Field Name = Test_Related_Formula_Text_Field_Acct
    Type = Text
    Formula = Account.Test_Formula_Text_Field__c
   

3. Ensure to add the custom formula field to the Contact page layouts for ease of replicating issue.

4. Create a Contact with no value in the Account field

5. Navigate to the new Contact and look at the “Test Related Formula Text Field - Acct” field

Expected Behavior: No value is display in the “Test Related Formula Text Field - Acct” field since there is no value in the Account field on the Contact record.

Actual Behavior: The value “Test Value From Account” is displayed.

Additional Notes: The unexpected behavior occurs when using other field types like Time. The expected behavior occurs when the field on Account (or the related object of the lookup field) is a picklist (even with a default value), and the resulting formula on Contact encases the picklist field in the TEXT formula function.

Workaround: Until this issue is resolved, the workaround is to add logic to display a null/blank value when the lookup field is null. Example formula workaround for our test scenario:

IF( NOT(ISBLANK(AccountId) ),
  Account.Test_Formula_Text_Field__c,
  NULL
)

Screenshot of Example:

Answer 1

I believe that this is expected. The reason why is that Salesforce presumes the default value for a field when no object is present. That can make all the difference when you do something like adding a custom currency field with a default, non-zero value, and then try to do math with it in another formula in a child object. I'm not sure why Salesforce does this, but I do know it that it does do this.

You should definitely check if a lookup field is not null before using a value from the parent field, especially when that value is a formula or a field that has default values. I'm not even sure that this is documented anywhere, but I have personally observed this in other projects, so I'm not even bothering to build a version in my org to "prove" this, because I feel like that's actually the behavior I've observed before.