Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
I was in Legacy Scoutbook. I used the link you have above and that tells me I don’t have permission to do anything. I can’t even get a scout record to come up.
If your connection to the Scout is as a MBC only, and you are clicking on their name on your connections page, this is a known issue. Otherwise walk us through what is happening.
A work around for the above is to use your Merit Badge Counselor menu on your dashboard to update merit badge work.