I am trying to make a unarmored defense trait on a homebrew race that consists of 
15 ac dex modifier.
I do
Set - Unarmored Armor Class - fixed value 5 (assuming dex modifier is already there)
but the weird thing that happens is when i make a character (tests have been with level 4 characters as thats going to be the starter level of the campaign im in)
it end results with 19 AC when i only have a 3 dex modifier so it randomly gaining 1 ac from the unarmored thing i made and i dont understand why.

any help with this would be greatly appreciated

Modifier: Set->Subtype: Unarmored AC->Fixed Value: 5

• That should be it. Did you accidentally select anything else from any other dropdown?
• Did you remember to re-save the feat after adding/adjusting the Modifier?
• Is your character equipped with anything that would change its AC (shield, magic item, etc)?
• Is there anything else that would change the character’s AC from class or feat?
• Does the character have an override on its Ac directly on the sheet itself?

I think I figured out or I can say what doing that seemed to so far of worked.
Tell me if maybe there is a cleaner way but,
what I did was
set - Unarmored Armor Class - Primary Stat DEX - fixed Value 5
then added
Ignore - Unarmored DEX AC Bonus
to remove the natural one and it seem to end up adding to the traditional scaling it would have with a natural DEX
it just now will say when you click on ac overview you no longer see the DEX modifier like you would normally with other races/classes
it just now all stacks onto the trait feature.

I will see if anything happens with some different DEX stats to see if it does work accurately. If this information I added helps with finding out how to make it work traditionally so you can see the breakdown better that be nice but I can live with it not working perfectly if need be.

Yeah, you shouldn’t need to do that. Try this instead:

Modifier: Bonus->Subtype: Unarmored AC->Fixed Value: 5

Lemme know if that works as expected please.

From what I can tell.

It does seem better, it doesn't break down the ac when you preview how it is to be,

but the fortunate thing is I no longer need the Ignore - Unarmored DEX AC Bonus and it is simulating what I want it to as far as I'm aware,
if for some reason it starts not working ill update but it seems to be working nicely as it is now

UPDATE: I realized it just needed a second to update now its working actually exactly as i intended it to, thank you for all the help you gave!