And this is why its a good idea to use a search.

Already known, discussed, flagged and being looked into by the devs.

https://www.dndbeyond.com/forums/d-d-beyond-general/bugs-support/9279-gnomes-dont-get-minor-illusion

As a current workaround just choose the cantrip you want and then make a homebrew feat to give you the cantrip.

This is still an issue, the illusion school doesn’t give the the new extra cantrip if you have minor illusion from forest gnome

Hello Anza,

Thank you for the report! This is a known bug that has been logged for a future fix. 

As a temporary fix, I might recommend creating a homebrew feat that grants you a cantrip, which you can then add to your sheet using the "Manage Feats" option in the character sheet view. 

Thank you!

and this is still an issue in mid 2019

It's a very small issue (coz gnomes, geddit? ... >.>) and you have an issue workaround of being able to just make a feat that gives you the cantrip you want. The devs are busy working on other projects that will be far mroe helpful to a lot more people. So, this issue probably won't get fixed for quite a long time due to the very low priority.

Still an issue.

Bump.

Still a problem. Forest gnome illusionist gets the minor illusion cantrip twice - once with "Forest Gnome" listed as a source and once with "Wizard" listed as a source - but the illusionist should be able to pick a cantrip other than minor Illusion at second level of they already know minor things illusion.

So I picked a forest gnome Which has the racial trait: Natural IllusionistPHB, pg. 37
You know the minor illusion cantrip. INT is your spellcasting ability for it.

I then chose an illusion wizard that has the level 2 trait:When you choose this school at 2nd level, you learn the minor illusion cantrip. If you already know this cantrip, you learn a different wizard cantrip of your choice. The cantrip doesn’t count against your number of cantrips known.

The problem is that it won't allow me to select a different cantrip to learn even though I learn minor illusion because of my racial trait.

This is a long standing missing feature. For now you can work around it by homebrewing a copy of illusionist and changing the cantrip.

I honestly have no idea how to do that

How to make a homebrew copy, how to change the spell, or both? I bet you can figure most of it out if you just poke around at the settings a while.

Both but I'll give it a shot

Well to get started, you need to go to creations - browse & create homebrew - create homebrew subclass - Wizard - school of illusion - create, to make a copy.

Then find the improved minor illusion feature - edit, scroll to spells - minor illusion - edit, then change the spell. You can make a selectable list by leaving spell name section blank and fill in class with Wizard and level with cantrip. Save (it will warn you it can't be published, but that is fine).

Then make sure homebrew is turned on for the character and change its Wizard school to the copy. It looks like a lot of steps, but it is pretty straight forward.

That worked perfectly, thanks for the help

Has any progress been made on this? It's not a huge deal, but my OCD hates seeing "Minor Illusion" twice on my sheet, and I can't remove one haha. 

No, progress hasn't been made according to the fact that I have experienced it again months later.  And it causes a lot of player confusion for games and new players.

[REDACTED] I am still getting this error showing up in my games and how it consistently causes issues for me and other players.  [REDACTED]

Anyways... I'm done with reporting bugs.

Have you considered doing the work around explained in post 32?

The Forest Gnome's Natural Illusionist ability (PHB) gives a character the minor illusion cantrip as a bonus cantrip.

At second level, a Wizard who chooses School of Illusion (PHB) gains Improved Minor Illusion, which says: <blockquote> When you choose this school at 2nd level, you learn the minor illusion cantrip. If you already know this cantrip, you learn a different wizard cantrip of your choice. The cantrip doesn’t count against your number of cantrips known.

...</blockquote>

As a forest gnome choosing school of Illusion would already know this cantrip, they should learn another Wizard cantrip, but no option exists for selecting this new cantrip.

Hi everyone, bought the Player's Handbook and I just leveled a Forest Gnome Wizard to level 2. I've decided to take the School of Illusion as my Arcane Tradition; however, because my Forest Gnome already knows Minor Illusion due to his subrace, I now have Minor Illusion twice on my character sheet. How can I decide to choose another cantrip?

EDIT: I had no idea that this was an issue for over a year. I'll try what post #32 suggests.

EDIT: Tried post #32's suggestion; works like a charm!