This occurs in 944 (latest as of June 17th).

World link as an example:

To demonstrate, join the world with two accounts, go to the player signup panel directly ahead of spawn, click "Add Me To Game" with both accounts, then have the non-master of the instance (who will have a delay in seeing their name appear, latency-depending) click the start game button.

The start game button runs SendCustomNetworkEvent to the owner of a different object.

Expected:

The owner of the object has the "StartGame" event called.

Actual:

Nothing happens, and the non-owner receives a console log such as the following:

2020.06.18 01:48:23 Log - [VRC_EventDispatcherRFC] Will execute SendRPC/AlwaysUnbuffered on StateMachine (UnityEngine.GameObject) for FairlySadPanda addd: S: "UdonSyncRunProgramAsRPC" I: 2 F: 0 B: Unused (non-local non-master non-owner)

2020.06.18 01:48:23 Log - [Network Processing] RPC UdonSyncRunProgramAsRPC/Owner abandoned because target player FairlySadPanda addd was not owner

(In this instance, another account - FSP_Test_1 - was the owner).