I tried kill some mobs today and the failed to cast is happening again. It seem to happen on any skill were casttime is > 0. Movement and interaction with npc's seems to work normal. This is 3rd time this has happened in few years. I suspect it being caused by something rom toggles when they do maintenance.
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Its back to working now. One of these days I may find what its affecting. It seems to be in bot.lua or player.lua