Issue when giving overall extra credit with weighted assignment groups

[MGh9]

(I am new to Canvas, so perhaps I am missing something obvious.)

Issue #1: I want to create a separate assignment group for Extra Credit which can boost students' overall percentage grade by up to 1%. My other assignment groups add up to 100%, and every assignment is in points, not %. In my Extra Credit assignment group, I have one grade worth 3 points.

Suppose a student has a 60% average and has not earned any extra credit. When I have the Extra Credit category counting as 0%, I see their average (correctly) as 60%. However, when I increase the Extra Credit weighting to 1% (so my assignment weightings now total 101%), that student's average drops to 59.4%, so it's like Canvas is normalizing my desired 101% possible back to 100% and that student is penalized for not having any extra credit.

That seems to contradict the "Create Extra Credit using Weighted Assignment Groups" section of https://community.canvaslms.com/t5/Instructor-Guide/How-do-I-give-extra-credit-in-a-course/ta-p/1253 which shows 110% total (but I can't see what the "2 rules" are there.)

Issue #2: Even though I have set the options for that one 3-point assignment to appear in points rather than %, Canvas keeps showing it as % on the Grades page.

What am I missing?