At what level are the cantrips gained from Magic Initiate cast?  

I know the spell is cast at first level.

Cantrips always scale based on character level

Thanks, that's what I thought.  Must be a bug in DndBeyond's char builder.

What bug are you seeing?

Cantrips are always cast at “Cantrip level.” The effects of some (not all) cantrips get stronger based on Character level, but the cantrips stay cantrips.

I have a 12th level Bard with Magic Initiate (Warlock).  I've selected Eldritch Blast, Booming Blade, and Expeditious Retreat for my feat.

On the char sheet,

1.) it doesn't even give me the option anywhere to roll the Booming Blade damage.  I've checked both on the list of cantrips and on my melee weapons.

2.) It lists 1d10 for EB damage.  When I click on that damage, it rolls a single d10.

Quote from Wren_the_Munificent >>

I have a 12th level Bard with Magic Initiate (Warlock).  I've selected Eldritch Blast, Booming Blade, and Expeditious Retreat for my feat.

On the char sheet,

1.) it doesn't even give me the option anywhere to roll the Booming Blade damage.  I've checked both on the list of cantrips and on my melee weapons.

2.) It lists 1d10 for EB damage.  When I click on that damage, it rolls a single d10.

 1) Check under spells.  Spells without an attack roll do not automatically show up on the actions page

2)This is displaying correct.  EB at 12th level allows you to shoot 3 bolts, so that is 3x 1d10, not 3d10.  If you read the notes on EB it will say "Count:3"

Post a link to your character so someone can look at it.

For Eldritch Blast, the damage doesn’t go up, the number of attacks do. Each ray makes a separate attack requiring a separate attack roll and a separate damage roll for each attack.

Here's my char

https://www.dndbeyond.com/profile/Wren_the_Munificent/characters/437447

So the booming blade you chose is not the official spell, it is a homebrew - material component is "a cup of water" and it says "Version: 1" not "Source: SCAG."

Quote from Wren_the_Munificent >>

Here's my char

https://www.dndbeyond.com/profile/Wren_the_Munificent/characters/437447

 

 Eldritch Blast is displaying correctly as I stated before: “For Eldritch Blast, the damage doesn’t go up, the number of attacks do. Each ray makes a separate attack requiring a separate attack roll and a separate damage roll for each attack.”

Your version of Booming Blade is homebrewed, it must have been coded improperly by whomever built it.

Just to mention: Booming Blade doesn't show as rollable anyway. It just adds a note to weapons listing the extra damage - as a note, not something you can click to roll. This is because it is "additional damage" to a weapon attack or a secondary effect and not "direct damage" on casting. If you have no weapon, the spell does nothing. So homebrew or official, for Booming Blade (and its alternative Green-Flame Blade) you'd need to create a custom attack action for it to be rollable-on-click.

Thanks go to all of you for your help with this.