Enemies not appearing - SMW Hacking Help

So i am having a problem with enemies dissapearing or even glitching: here is an example:

Even thought there should be 2 red Koopas there is Only one, there is even times when there's none, when i stomp them, they don't exit the shell, and even one time a shell with garbage graphics appeared.
Also seems to happen if i go past the midway point without dying.

I have gotten the same error in another level, and it seems that most likely it's the Hammer Bro, since ii is present in both levels with this problem. Still, i am gonna pass every Custom sprite in the level in case it's actually other sprite:

Dissasembly of the Koopas
Custom Venus Fire Trap Pack
Hammer Bro

And That's it

I'm also using SA-1 (2MB)

The most likely explanation is that you've hit the sprite limit in the level. SMW has a maximum number of sprites that can be processed at any given time (12 in the original game, 22 with SA-1), and once that limit is reached, the game won't spawn any more sprites until old ones are despawned.

It doesn't look like there are that many sprites onscreen in that screenshot, but it's possible the cause may due to some sprites you've used earlier in the level. Certain sprites in SMW, particularly carryable sprites like P-switches and springboards, are treated as permanent sprites and won't despawn when scrolled off screen. So if you have a bunch of those present earlier in the level, they may be taking up all of your sprite slots. Alternatively, one of the custom sprites you have may not be getting despawned for whatever reason either. If it's the custom sprites, try deleting earlier sprites one at a time until the issue appears to go away, at which point you know which sprite is causing the problem.

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That is what i've been thinking, and it is most likely the hammer bro, but it could also be a combination of all of them... I Will try and come with news

It seems that it was the hammer bro, while in one level i removed a party of them, in the other i split the level in sub-areas. That may explain why i saw more than 8 hammer Bros in other hacks.

Are you using NMSTL (No More Sprite Tool Limits)? If not, you should set it up here (it should automatically be set up with SA-1), oh, and make sure you use sprite memory header 08. That should fix your problem.

No, i had not used Sprite header 08, but i got the idea of splitting the level in half with a pipe... but thanks for the reminder.

Could also be a glitch with vanilla SMW

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I dont think it is a glitch of SMW itself, but probably due to a custom enemy, with the main suspect being the hammer bro, especially since in levels that i have with tons of enemies, all of them appear as intended.