In viewing Student Results for an embedded Studio Video Quiz in two course sections, I am only able to see Attempt 1. To check, I've used the Test Student to take the quiz again with a better score (100% vs 75%). Only the first lower score shows in Student Results. This is true on computer as well as in the Canvas App.
I've cleared cache and browsing history, made sure browser is up to date, shut down and restarted device. There are no settings in Studio that limited attempts to only one. It is the same video quiz I used in a previous semester -- also two course sections -- in which I had no problem with viewing individual students' repeated attempts.
In viewing Quiz and Item Analysis, though, the lowest and mean score are higher [Low 75%, Mean 89%] than those for the class's Attempt 1 data [Low 50%, Mean 75%]. As well, the Score Distribution bar graph also shows a lower number of students with a poor score and a greater number of students with a perfect score than the Attempt 1 data, verifying that some (myself as Test Student included) made at least a second attempt.