Okay, so I’ve been trying to make a fire-ish place with a lot of different particles for fire, as well as smoke.
However, this happens:
https://gyazo.com/78ee63995ca59f230aeab21c0d428809
I have tried removing various smoke particles, as well as editing the particles - yet it seems nothing is working.
Does anyone know how to fix this issue? If so, thank you! 
I can’t say specifically what’s causing the issue, but I have a few ideas maybe.
How large is the map persay? Draw distance plays a large role into how particles/how many particles get drawn. Farther distances have a tendency to remove a majority amount of particles, even at full graphics.
Are the particles emitting from points? if that’s the case, especially for larger particles, if the point is obscured the particles might be completely negated from the screen.
And on that note, how large are the particles? big big ones generally have rendering quirks.
From what the scene is looking like, you have pretty large and abundant particles (I assume the big black cloud is one) I would tone it down or increase opacity to lessen the amount, alternatively, you can use billboard UI’s for virtually the same affect in most cases.
Hope this might help! I can’t really say a specific solution as you can go about it in a bunch of ways.
You’re using too many particles. You seem to have reached the limit of how many particles can show on your screen (IIRC 16k is the limit).
When there are over 16k particles in the area, particles will appear/reappear based on your camera’s position, choosing to render the ones that are the closest to you, and not rendering those farther away. It’s always trying to choose which particles should be part of those 16k and which shouldn’t.
To fix this, use less particles. You’ll surely have to make the exchange from many/small particles to fewer/bigger particles.
What’s your graphics level? I used to experience this on my low-end mac on graphics levels 1-3 with eg. the Jailbreak Clouds.
Good point. If I’m indeed correct, 16k is the limit for max quality level.
That limit decreases once you lower your quality levels.