Setting Attunement Slots

I'm homebrewing a warlock patron and one of the class feature gives you an extra attunement slot, making your total to 4. I've tried to make this happen by using Set- Attunement Slots and then fixed value of four but my attunement slots haven't changed and I'm stumped on how to rectify this .

That’s how you do it. I have a feat I made that does the same thing called Attunement: 

 https://www.dndbeyond.com/homebrew/feats?filter-name=&filter-description=&filter-author=IamSposta&filter-author-previous=IamSposta&filter-author-symbol=102118565&filter-rating=-10

 Can you explain how you do it. When I add a feat with the right setting, it's not setting the value.

Quote from Raknafein >>

 Can you explain how you do it. When I add a feat with the right setting, it's not setting the value.

 What setting? I don’t know what you tried, but this way has always worked for me:

Modifier—>Set
Modifier Subtype—>Attunement Slots
Fixed Value—>4

That will grant the character a fourth Attunement Slot. This is the version of the feat that I published for it, that’s how I did it. 
https://www.dndbeyond.com/feats/265761-attuned

I did exactly that on a feat. It change the value to 1 possible attunement instead of 4. But your feat work. Strange ah ah

Quote from Raknafein >>

I did exactly that on a feat. It change the value to 1 possible attunement instead of 4. But your feat work. Strange ah ah

 I’m glad mine works! Lol. That’s why I published it after all. 

Go back and double check yours to see if you put a 1 or a 4 as the fixed value. That modifier doesn’t add an Attunement slot, it hard sets the number of slots to match the fixed value. If you put a 1, instead of adding 1 slot, it will instead hard set the number of slots to 1. If you did put a 4 there, and it’s still setting the number of slots to 1, then that’s a glitch/bug.

Yeah, I understood fix value means it's a set value, it's not adding. So it's definitly a bug. Thanks for the answer my friend! Have fun with your DND games!

From a fellow DM :D

Happy to have been of assistance. 

And to be clear, I was in no way intending to talk down to you or anything even remotely like that. What with all of the various different  modifiers all working in slightly different ways or on different things I have helped others with that exact miscode in the past so I was just trying to be thorough. If I came across as condescending in any way I apologize. 

its also worth mentioning that you can never have any attunement slots greater than 6.  

You were not, english is not my first language, so it might have come accross as if I took it as condescending, but no worry didnt feel that way at all. You were helpful in narrowing out the possible mistake. I was able to confirm my problem was definitly a bug. By creating a new item instead of modifying, it worked afterward. Thanks for your time!

I can see that this works on Feats but, as I managed to create a Ring of Swimming using Heliana's Guide with and Enchantment Boon of an additional Attunement Slot, I thought I would homebrew the Ring so that whilst I am wearing it I get the extra slot.

I did the steps you stated, setting the modifier to 4 Attunement Slots.

I saved the Modifier and then saved the item.

I can add the item to my inventory and can see the description correctly, as well as the swim speed modifier.

However, the extra attunement slot is not showing up. 

Any ideas?