I feel like creating a list of utilitarian paradoxes. Did I miss any?

• Investing money increases the amount that you can donate. It seems that it's always a good idea to invest longer, but it's obviously a bad idea to invest forever.
  
• Pascal's argument: We must strive exclusively for infinite utility, as an chance of it will outweigh finite utility.
  
• Undefined total utility: If both infinite positive and infinite negative utility happen, the total utility is undefined.
  
• Undefined expected utility: If there is a possibility of both infinite positive and infinite negative utility, the expected utility is undefined. Also, if only finite utility is possible, but the probabilities don't decrease fast enough, expected utility is still undefined.
  
• Incomparable universes: If we take two possible universes that are different enough, it can be seemingly impossible to find a way to compare the two. For example, sentience being analog vs. binary.

You missed a few biggies:

Repugnant Conclusion - If adding additional persons slightly diminishes the utility of everyone else because of resource scarcity, and yet each additional person adds more utility than is subtracted, then the proper utilitarian response is to add additional humans until there are billions of people who experience only the faintest hint of happiness.

The Utility Monster - One being's marginal expected utility is always vastly higher and thus, by utilitarian logic, all resources should be used towards the utility maximization of this being.

Also, some of yours aren't really paradoxes.

With regard to investments, it has already been shown by members here that specifying donations be used for fundraising produces a return which is much higher than virtually any investment. Granted, this wouldn't work if everyone did that, but we aren't kantians now, are we.

Undefined total utility: If both infinite positive and infinite negative utility happen, the total utility is undefined.

It is actually 0, unless you are exclusively a negative utilitarian in which case it is negative infinity. If you are a prioritarian, then we must argue about whether there are greater and lesser forms of infinity, though I tend to think that there are.

Though this is really not that practically useful since the amount of utility we could ever possibly measure will always be finite, even if we were reaching some sort of Omega Point. Thus, any sort of concrete aggregate utility that we are actually concerning ourselves about will be necessarily finite.

I was thinking ones that cause problems for utilitarians themselves. I think the ones you listed are more for the arguments against utilitarianism.

The investment one is really only true if you assume the universe would go on forever, but I felt like including it anyway.

Infinite positive and infinite negative utility are equal if they are both infinite. It's not really clear what it means to add them. I put it as undefined as it destroys the normal rules of arithmetic. For example, adding positive utility won't increase the total amount. It's important if we ever discover a way to make the universe last forever. The laws of thermodynamics might be wrong. They certainly don't apply to general relativity.