Changed the sprite/flipbook, and it's still not working. I think it's may be something in my blueprint for this particular enemy.

The problem of "I cannot see something" could be many issues. You've got visibility flags, alpha, lighting, positioning, culling, texture errors, material errors, model errors, and much more.

You posted in mobile and tagged it as Android. Does this only happen when you run on the device? Or does this happen if you run on the desktop as well?

Yes it only happens on the device. It works fine in all ue4 play/simulation modes.

The device is a Note 5. My buddy is coming over with an iPhone 6, and we're going to see if it happens on that too.

I just tried to fully package the game and run it on my Note 5, but the same issue occurs. I'm not seeing any errors or warning when I compile the game. How can I debug the game on the phone?

From the docs, it looks like you need to install their custom Android SDK project "Android Works". You'll also need to tap the build number until you are in developer mode, attach to the ADB debugger, and follow all those steps.

Make sure your textures are the right format for your device to eliminate that potential issue.

Then check the program logs. They might be in \MyProjectName\MyProjectName\Saved\Logs, or you can access additional logs through adb with: adb logcat -d > my_device_log.txt

I appreciate your help! I'm just a modest designer.

Can you post the link of the particular docs you're looking at please.

Also, where can I check for the correct textures?

In the most recent logs I find no errors or warnings.

The symptom is the enemy is invisible but fully functions. What are common solutions to that issue?

Thanks much!

Update: I ran my game on not just the Note 5, but a iPhone 4s, 5, and 6 Plus. Same issue occurs in each instance.

The part of my character that isn't visible on mobile is a Paper2D sprite Flipbook.

I hope this additional information helps.

I appreciate your help. Here are some screenshots that may help diagnose and resolve the issue.

Enemy Blueprint, Enemy Viewport, World Settings and the Flipbooks settings.

Let me know if I can add anything else to help. Thank you!

What are common solutions to that issue?

Graphics that are of the wrong format, models that are incompatible, lighting that is not configured correctly, shaders that aren't compatible with the devices, and more.

The documentation covers these limitations, I suggest working through this, this, and this, ensuring they have settings that are compatible.