Descriptive Problem Summary:
If you have your client.eye set to an object that is farther than 12 tiles away from the mob the client is attached to, adding a verb to the mob will not have it show up in the client until the eye is moved back within 12 tiles of the mob.
I asked around, and was told that 12 tiles was Byond's occlusion range.

Numbered Steps to Reproduce Problem:
1. Put your client in a mob
2. Set your client.eye to something that is farther than 12 tiles away.
3. Add a verb to the mob your client is in.
4. Note that the verb does not show up in your client.
5. Move your client.eye closer to the mob
6. Notice the verb update and appear.

Expected Results:
The verb would appear in the client regardless of distance to the mob

Actual Results:
The verb doesn't appear until you get back within occlusion range.

Does the problem occur:
Problem occurs every time for different users as well.

When does the problem NOT occur?
The problem doesn't occur as long as the client.eye is in the

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked?
It occurred in earlier versions as well.

Workarounds:
Keep your client's eye within 12 tiles.