In previous versions of Minecraft, I was able to use SendKeys (through powershell, VBScript, etc) to open the chat window then enter commands. In 1.13, Minecraft ignores the chat key (t) when sent using sendkeys but if I press it on my physical keyboard then the chat window opens and then the rest of my command can get entered through sendkeys. The Enter key also doesn't get pressed when sent through SendKeys. This is affecting my ability to build large projects using commands and scripts since RCON still isn't thread safe so I can't use that method either. So far I don't have a decent workaround other than building in 1.12.2 then upgrading the world.