When adding scores to objects that existed prior to the Infer AppExchange package being installed, it is possible that certain older objects are not in compliance with newer validation rules. In this case, Infer’s attempt to write to these objects will fail.
When this occurs, the Infer User needs to be exempted from the validation rule in question in order for Infer to access and score the object.
The easiest way to get around this problem is to bracket your entire validation rule and add the following snippet to the rule:
&& $User.Alias != 'Infer'
Note that the snippet above is case sensitive, so you also need to ensure that the Infer user's alias is 'Infer' and not 'infer.'