Run launcher as admin. and do add the iMU folder to your mcafee, i know mcafee do alot of updates and blockings so its possible it changed in their settingsI'm actually having the same problem. Tried to remove DEP setting from mu client as Venci said and I never had problems with my antivirus and iMU. It was working perfectly yesterday but today it flipped and no game pops up. I already reinstalled the game.
Link: https://www.youtube.com/watch?v=BN9kX2Xzrmw
The same thing happens to me, I needed assistance. RESiSTANT can help me pleaseRemove DEP setting for MU client , restart PC and try to connect again. If still does not work, then contact me via Discord for remote assistance. My discord is: VENCi#3206