Hi @sudosaurus ,
Is your column Assessor a Person column?
If yes, I did a test on my side for your reference(My Person column called persondefault1).
Inside the gallery, add a Image control and set its Image property using below formula:
Note: Actually we can directly use Office365Users.UserPhotoV2(ThisItem.XXX.Email) to display user profile photo. But for avoiding "invalid value for the userId parameter" error, we need to add some judge conditions using If function.
If(
!IsBlank(ThisItem.persondefault1.Email),
If(
Office365Users.UserPhotoMetadata(ThisItem.persondefault1.Email).HasPhoto = true,
Office365Users.UserPhotoV2(ThisItem.persondefault1.Email)
))

Then add a Label control inside the gallery and set its Text property to:
ThisItem.persondefault1.DisplayName

Best regards,
Allen